Well..I watched the tape of Sly.
My take: The wierdness (if you want to categorize it as such) was intentional. In a nutshell - I think Sly knew exactly what he was doing (maybe he's not as fried as we think?). I think it was a minimal effort to be sure, made for some reason we can only speculate about, but after reading this thread I was expecting a lobotomized zombie...and that's not what I saw. He knew exactly what he was doing. He did it and split. The accompaniement was noisy, self serving bullshit (I'm sure he knew that).
His physical appearance ? i.e. the mohawk,etc. That's what Sly thinks today's show biz wants. That's all that is.
Disappointing in the sense of what an appearance of Sly could have been was not realized.