They'd probably respond, "Easy, you pass a law saying that anyone who uses such-and-such kind of math shall be punished with fines or prison." I get what you're saying, but I think they might miss the point.

Plenty of countries outlaw certain uses of words, which is not much different.

Here's the problem. We can talk tech all we want, but you have to reduce modern politics down to a catch-phrase that makes your opponent look stupid. You make anyone who tries to ban encryption embarrassed and make others call them stupid. Hell, pull out the card deck and say they're trying to ban a card trick. Logic is so long dead in politics that you got to go for the emotional gut. Bonus, if you can phrase stuff in such a way to make them unpatriotic too.

I'll go be sick in the corner now from writing the truth of it.