As his illness worsened, I think it's possible that others contributed more, but I'm not sure that the way he approached his creative work changed in some fundamental way. It becomes a question of extent and practicality.
Yes, it becomes a question of extent.
If Brian only contributes 30 percent or 20 percent to a song, rather than 50 or 60 percent, does that make the song irrelevant?
Not totally irrelevant, but less relevant.
And if a session needs to be done, or a date needs to be played, and Brian isn't feeling great and others take up the slack, does that poison the well forever?
See the above responses. The less Brian contribution, the less I'm interested. I don't have the same emotional response to the others who may be performing "duties" for Brian.
And ultimately, what's the alternative?
Credit the album and the concerts as The Brian Wilson Band. It'll never happen for obvious reasons that don't need to be discussed. But, at least it would be honest and not deceptive.
If, SJS, you've seen how people with such illnesses benefit from coaching, then why shouldn't Brian benefit in that way?
Brian should benefit in that way. But, like I intimated in my above post, when the coaching turns into actually doing the work for the person - like writing the music, producing the track, picking the final tracklisting, sequencing the album, choosing the artists to duet with, etc. - as much as it is well-intentioned, it becomes more and more the vision of the collaborators and less and less the vision of Brian Wilson. And that's important to me. And, like I mentioned above, art is a unique and personal thing. It's one thing to help a person learn how to use a computer. It's another thing to write/arrange/produce/record music for them - and then have them call it their work.
Should he simply not play music in public or release records?
Not simply, no. This might surprise you, but there is a lot of what Melinda does with Brian that I agree with. Influencing the music end of his "career" is not one of them. I think Brian should've released albums when HE HAD enough material to fill an album. Don't artists/musicians record albums because they have something they want to say and actually have enough songs to fill such album? Didn't the live albums and covers albums and numerous re-recordings send up a red flag? And, yes, it depends on the project as to whether I feel it should've been released. I didn't agree with Pet Sounds Live being released on CD, chiseling together GIOMH, quickly throwing out a Christmas album that incorporated old Beach Boys' Christmas songs/re-recordings, the Disney album, and you know how I feel about the re-recording of the SMiLE tracks. I think Melinda's philosophy of a constant flow of Brian Wilson releases did him a disservice. And, I think the albums reflect that.
And what if he indeed wants to do so, regardless of his illness?
If he indeed wants to do those things, sure. But that's really the question, isn't it. In addition to being mentally ill, many times Brian is full of sh*t, has a problem telling the truth, and is known for playing games with people. So, YOU have to make up your mind as to what you believe, and I'll make up mine.
Or does this turn into a story of others manipulating him for their own ends again?
I won't go as far as saying he is manipulated. I do think ideas are formulated by OTHERS and presented to him. As I mentioned ad nauseum, I preferred it when the ideas originated with Brian, especially musical ideas. I think it's a combination of the people making the ideas/suggestions being very persuasive (I'll leave it at that) and Brian "just going along". At that's not to say that ALL of the ideas come from others. I've never said that. Now I'm going to repeat myself. The more ideas and suggestions that come from others, the less come from Brian, the less the project becomes Brian Wilson's. And I prefer more Brian Wilson than less.
Finally (I hear people clapping

), the recent Jeff Beck "episode" encapsules a lot of what I'm trying to say and how I feel....Jeff Beck was brought in to collaborate with Brian. Whose idea was that? First we see the photos of a smiling Brian and Jeff together in the studio. Surely they must be hitting it off, sharing ideas and making great music together. Then we see photos of Brian at the board. I'll bet he's producing those new Wilson/Beck tracks. Then we start to read things from Brian's "associates" about the Beach Boys' genius and the British Guitar God "huddled together" in the studio; the results should be mind-blowing.
A few weeks later Jeff Beck is quoted as saying that Brian barely acknowledged him, sat silently in the studio, barely offered a suggestion, didn't get much done, and on and on. But, what if Jeff Beck didn't come out and say those things and the songs got released (and maybe some will)? Fans would be saying, "Brian and Jeff collaborated great." "Those were Brian's ideas, I just know it." "In the studio Brian is a different person." Do you see how it works? How am I supposed to feel about any Wilson/Beck tracks that might come out, knowing what I/we know now? That's the whole issue in a nutshell right there. Hey, I get it. I know how things work with the photos and the optimistic pronouncements. It just that I've seen this "game" played over and over, going all the way back to 1976 with the Brian Is Back campaign. It gets tiring. Actually, I'm jaded. And cynical. Being a fan of Brian Wilson has worn me down.
This is all I have to say tonight. You'll be happy to know that I'm burning out on this subject and I don't have anything else to say tonight. Maybe tomorrow...

I'm sorry you feel that way, SJS. It's especially sad for me, given the great joy I've experienced from Brian's solo work of the last 20 some years. There's nothing really profitable to be had from this discussion at this point -- I can't say anything more or more eloquently than Ray Lawlor, who's a personal friend of BW -- and you don't credit him for much either. Which is okay. Sometimes we have beliefs that are so strong that we simply know them to be true. And when I write that, I mean it to be about you, but you probably think it describes me. Which is okay, too.