Handling gish gallops is easy for anyone ready to field them.

You pick the easiest thing they spat out to dismantle, explain that they’re gish galloping so you’ll only address the thing you chose due to time constraints.

You let them give you the meatball to knock out of the park and point out their shit rhetorical devices. Then it’s obvious the next time they do it, and you do it again. Then they’re naked.