If he still has the obsessive mentality like he did when he was a strict Vegan, he'd probably do well pivoting his channel's content to a weight loss arc. Probably the smartest thing from a business sense too, these eating/mukbang videos aren't as popular as they used to be and his online celebrity status is pretty big.
That said there's a lot of variables and barricades. People do change a lot in their 20s/30s still and he might just not have that fortitude anymore, Orlin has to be onboard with losing weight if they stay together, and it's going to be a lot more expensive to buy trainers, therapists, doctors, dieticians, etc. (even if it's just used for content) than buying the fast food menu and make enough content or find a way to keep monetizing it. He's bound to have a lot less people interested if he's not eating to himself to death as a morbid curio and he has to persuade even people that "genuinely care" about him that it's different this time and not a stunt.