it's true they can't cash out those bitcoins that easily
but these aren't amateurs, they pulled off a multi year offline key reconstruction
i'm sure they already considered the tainted coins before moving a single bitcoin
mixers, OTC deals, and layering exist for exactly these kinds of situations
we've seen plenty of exploiters from past hacks still living freely years later
you're delusional to think they'll accept "5% audit fee"
why would someone who managed to brute force weak entropy settle for scraps when they can wait, test different laundering routes, and move at their own pace?
at the end of the day, they stole the money
one way or another, they should end up in jail not be offered a deal