I know this is going to sound like some clickbait bullshit title, but I’m genuinely curious, asking in good faith. My two oldest sons are enamored with him, and he seems like a genuine guy, so I’m asking - is he a nice guy? If you google the question, you get a bunch of reddit hate, which I don’t always trust, because…it’s reddit. I have not watched much content (not my thing, I’m old) but I’m just curious what the fediverse has to say.
There is at least one video (maybe an interview, not necessarily on his main channel) where he talks out of character about how he runs the channel etc.
His on screen persona is just that, a persona. This is something your kids should understand (and they can, if you find one of those out of character videos).
That said, I believe Jimmy Donaldson (the person behind the on-screen persona) does genuinely seem like a good guy, who is also smart and knows how to run a successful business while entertaining people. He also talks a bit about clickbait and how he tries to not make it too extreme but has to play the game.
Depending on how old your kids are, it may also be worth talking about the business aspect (sponsors, merch, the various brands he creates, how Beast Burgers actually works with ghost kitchens etc., Feastables) - no need to criticize or put it in a negative light, just explain that it’s also a business.
Wikipedia has some notes about controversies and criticism.