My wife does something similar to me all the time. If she knows that I’m uncertain about a fact, she’ll feign a kind of mistaken certainty in the (true) fact to bait me into taking a bet against it. Then I lose the bet.

Same thing in politics - If you know the other side is uncertain about a position that you have high confidence in, stake your position and then politicize it so the other side is forced to either concede or stake their claim to the weaker position.