I think Beef's in persona mode, like with Notorious L.I.N.C.O.L.N. Since he's not Beef he can be more outgoing.
Yeah, we are definitely talking about persona-Beef here. Beef seems to be able to be assertive and extroverted when he's shielded from consequences -- not just when he's in a persona (L.I.N.C.O.L.N. or the Animalicious frontman) but also in situations like his rocket theft and trip to the moon, when the others can't possibly punish him for being "transgressive."
This is why I like Beef; there's always some interesting stuff going on below the surface. Even if that means becoming Devo.