I'm not sure if you understood my post right. Bitcoin mining relies on ASICs. If the NSA wanted to do a 51% attack, then they'd have to spend a bunch of money b

I'm not sure if you understood my post right. Bitcoin mining relies on ASICs. If the NSA wanted to do a 51% attack, then they'd have to spend a bunch of money building ASICs that are then worthless to them once they're done with their attack. If Bitcoin mining relied on GPU or CPU computation, then the NSA could just redirect some of their existing GPU/CPU hardware to do a 51% attack, and then go back to using it for something else when they were done. It would be cheaper and easier for them to do.