So obviously that argument is stupid. But I don't think it is a conversation halter. I think it is the case that you have to assume something in order to draw conclusions at all (and I think there are probably a couple more of these in addition to induction). So once we've said "we're allowed to assume this" obviously our debating opponents are going to want to assume things of their own. The right response to that is not "AHHHHH! CONVERSATION STOPPER!" Rather, we need a language for distinguishing good assumptions from bad assumptions. So this move shouldn't stop the conversation. Rather, it leads to a conversation about what makes some assumptions justified.

ETA: And

In the realm of physical reality, reality is one way or another and you don't get to make it that way by choosing an opinion, and so some "assumptions" are right and others wrong.

Just isn't going to be the kind of language that lets us evaluate assumptions. The whole point of assenting to any assumptions is just so that you can say something true or not true.