I wouldn't pay particular heed to any negative opinions of him from Bayern fans. Whatever he did/didn't do, he couldn't be expected to play regularly there, and when a player is then linked with moves away, it creates a confirmation bias in fans' minds that he isn't good enough, and never will be.
They might be correct in that assessment, but its very subjective given what they are used to, and doesn't mean he can't fit someplace else.
This seems to be our proposed solution for back-up, and we need that back-up in.
He wouldn't go to the U23's, so if Ancelotti thinks its worth a shot, and at the fee mooted, then it is worth a shot.