Maybe they should not. I see absolutely no reason why you would find it worrying that they cannot. That's basically just being worried by the sovereignty of other nations; worried that you can't boss other people around... what a perverted concern.

If bitcoin is only worrying to the extent that foreign currencies are worrying, then I don't see what the big deal is. They cope with the existence of what, 179 foreign currencies right now (minus a few pegged to the dollar, but whatever)? They can learn to cope with 180.

Worrying to the OP - I find it enormously interesting.

And at least in the case of the US they can (and do) lean pretty hard on any of the other 179 governments when they really want to. There is no central Bitcoin bank to lean on. That's all I'm saying.