I don't get how anybody gets so angry about how someone else chooses to practice an art-form. Nobody's stopping him from doing improv however he likes, so why get so annoyed because someone else it doing it another way? All I can think is that he's feeling bitter and underappreciated.
He was in an improv group with Stephen Colbert and Steve Carrell once so I guess he's always comparing himself to them and feels like he's coming up short.