The nicest and most ardent fans among us can get caught up in the moment or clash with someone around them in any number of scenarios.
It’s part and parcel of the deal.
The stadium chair thing, however, is a specific action that is very fixable. I am not terribly fond of solutions via executive fiat, but sometimes this is appropriate. It seems to be such a case here. A ban with holding areas for home-brought seats and cheap rental alternatives seems superior to the status quo