Okay so, bad news. As I'm sure you've all noticed, 1.0 didn't fix master hand. This is really unfortunate and I'm just as sad as you are.
I really want master hand to work as well, so I'm going to try and fix him myself. Please note that will require an entire rewrite of his logic, so it may take a while.
Please be patient but I'm going to try my best!

Yes unfortunately that is a bug that happens at the moment, he can just travel through all the stages. It's a game bug that was introduced in one of the updates preparing for the new custom stages, I have informed the devs about it and I'm crossing my fingers it will be fixed when the next update launches in July!

He went through the stage and KOed himself

Yeah for sure, it was pretty difficult to implement him as a floating boss with the tools available so there can be glitches.
Most notably he has started going through stages which is a huge issue but that is beyond my fixing, I'm just hoping the devs fix stage collision soon.

Good on the surface, insanely glitchy when playing