They can sue for damages, because the clean-hands doctrine doesn’t apply to suing for money, only applies to suing for equity (anything that isn’t money).
The doctrine if unclean hands may only be used as a defense in claims of equity – which are claims in which the court seeks to make things equal or fair, though not by ordering the payment of damages
IANAL - just noticed that and thought you might find it interesting…
That's my understanding as well, but lacking the knowledge to remove DRM and willingness to become a target of a lawsuit to prove a point I am not going to test that legal theory just yet.
If Voice.AI attempts to enforce their ToS anyway, they are violating the GPL. IANAL, but because of the clean-hands doctrine, such a suit would fail.