VERY perceptive question, reader Camille. Pâte à bombe is of course the delicious base of whipped egg yolks and sugar syrup that’s often used to make chocolate mousse. “Pâte” is variously translated as “dough”, “paste” or “mix.” And “bombe” as we’ve established pretty much just means bomb. I think the only possible explanation is that pâte à bombe is/was a base that’s employed in the making of dessert bombes.
But didn’t you say that bombes are classically made with ice cream and not mousse? To my understanding, yes. However you can use pâte à bombe as a base for ice cream. I’ve never tried that, but I’d be extremely interested.