Two sides to every coin. They know very well that once everyone accepts that deepfakes exist, and that nearly anyone can make them, and they are difficult if not impossible to identify, then the age of photographic and video evidence is over. They want deepfakes out there because it means that if they get caught on camera or on a hot mic, they can immediately turn around and claim that it was a deepfake. Their base will believe it. It will be virtually impossible to get republican voters to hold them accountable then.

Edit to add: The GOP base, being what they are, will gleefully believe deepfakes about democrats while completely dismissing those about republicans. It really is a win-win for them.