It's hard to believe Mosconi said anything like that about anyone. He wasn't that kind of a guy. Gene knew about the comment, as he had a copy of the book, but he never knew for sure whether or not Mosconi actually said it. Mosconi was never asked about that alleged comment to my knowledge, so we'll never know.
I don't have any information on how Mosconi felt about Gene's game. Gene said he wishes he knew then what he knew in the future. He felt his form back then was all wrong.
I'm pretty sure I read somewhere that Mosconi, later in his life, was asked about the comment and denied making it. IIRC, he said something like: why would I say that? But I don't know when he was asked. And it is worth noting that sometimes Mosconi said he missed and sometimes said he just quit on the 526, so who knows. Mosconi died with Alzheimer's.
Lou Figueroa