I'd have to hear his input on how easy he might think it would be to do that protocol with pen and paper

not easy

for hedgehog to work you have to create a preimage & hash in every transaction, as well as two bitcoin signatures. A guy in this video shows how to create a preimage & hash with pen and paper. It looks like it would take about 8 hours of full time work and you'd probably make a mistake somewhere, so you'd likely need a team of three people to check your work. It is my understanding that creating a signature manually is about twice as difficult as creating a hash manually, and you need two of those per transaction so it's about four times as much work to make the signatures. So you're looking at five days of 8 hours of work for a team of four people -- per transaction.

But why do this with pen and paper? In this hypothetical scenario, did the USA also confiscate and ban all graphing calculators? It only takes a graphing calculator about a second to calculate a hash or a signature, so you'd simply have to program it for that -- and I'm sure such programs would be released as shareware. (There's one for gameboy already, so start with that and modify it for a ti-86, which should be easy because they are both 8bit processors with Assembly support. Or literally use a gameboy.)