sure they can take the money back. they just make wikileaks pay them, or else they press charges against wikileaks for holding onto the proceeds of crime or whatever.
even if you're insisting that censorship has to be preemptive, then the chilling effect from these arrests still counts.
"What about the rubber hose" is an entirely valid security concern in some contexts and is part of why the principle of least privilege is important.
Whether you think it's fair to call this "censorship" or not, the fact remains that the state can control how its citizens use the blockchain, because it can control its citizens.
even if you're insisting that censorship has to be preemptive, then the chilling effect from these arrests still counts.