He's already better off than in his past life, don't ask for perfection or this comic will become tastless and annyoing, with only a guy flexing his wealth around as a billionaire.
Sure, there's better things to do in life than playing with your colleagues when you're more mature but that's a realistic situation when you start University, since obviously, some are more mature than others. Would you rather theses people didn't interract with others just because girls want to date them or guys want to be douchebags with them ?
He should be able to express himself imo, moreso as an experienced middle aged man, to give them some hindsight and not let them f* up the class atmosphere. Anyone has this right, even. If you don't like him, then that's on you