Let's help them out. How would *you* write the law making Bitcoin illegal? I guess it would require a definition to label it. It would also need an action that would be observable. I'm just wondering how it can be done without making teaching math itself illegal.
"Participating in ownership of transfer of Bitcoin is aids and abets terrorism, threatens national security, and the perpetrator is classified as an enemy combatant in the global war on terror and is treated according to current protocols on the matter."
I may or may not need to remind people that currently in the US 'enemy combatants' no matter what their nationality and location are subject to extra-judicial actions up to and including execution.
There will probably be a golden window where very few people understand Bitcoin and are involved in it. That could be the best opportunity for a severe clampdown as the vast majority of the population would buy any story-line (particularly after a few false-flag events) and very few families would have a family member who was neutralized.
In spite of my paranoid ramblings on this topic, I think it
unlikely that things will get 'that bad' and indeed it is likely that nothing will happen at all. But if I were charged with the engineering challenge quashing Bitcoin in a no-holds-barred type of way, I think that would be the most effective way to do it. We (the US) already have the infrastructure in place for such operations after all, and since building up the infrastructure has been politically costly I am guessing that there was an offsetting reason for getting things set up.