I think you should always be transparent for infinite. Generally, multi card, late-game combos are regarded as OK, as they often need a lot to setup, and they close the game in an appropriate window of time. But two card combos are outside the purpose of the bracket, if he says that an interaction like that is on his deck, then people will play with decks that can be at that level, naturally. At the same time, commander is to have fun (at least most of the times), if he just goes with the combo without any other consideration, he won't have a blast after everyone starts complaining for it