I mean this kindly, but I think you should examine your standards of evidence a bit.

Consider that this guy has gone on record saying he's in danger for revealing this information, but stops at actually releasing the classified documents he has seen.

In order to publically speak about what he's talking about, he would've needed to go through a standard security process whereby he was essentially told what information he was allowed to reveal and what he couldn't. So you need to ask yourself; if the government is running these secret programs on UFOs and is in league with killer aliens to blackmarket their tech, why would they sign off on him revealing that information, but the documents he has that aren't even first hand evidence are a bridge too far?

There's a good video by a guy named Nick West that points out some gaps in the logic of Grusch's claims and why they're most likely not true. Grusch doesn't necessarily need to be a bad actor, maybe just honestly confused or mistaken, and I myself would very much like for alien contact to be real, but I don't think this is it. It's us being told by a guy who got told by some other guys that a thing happened and no one is ponying up any hard evidence, which to my mind isn't very strong.