...and as such, I believe discredits the theory the FBI was able to hack the hacking group.
I see, thank makes sense. So if we rule out the possibilities that an exchange just handed FBI their key; and that the FBI hacked the hackers; and (of course) that FBI cracked bitcoin with quantum computers... what are the odds?

Could it be possible that the FBI somehow scammed the hacker with their mixer, and then applied for a warrant to move the coins further?
..I'm also surprised that the hackers didn't even bother to try something like CoinJoin first.