Most jams either are there for getting opinions on your game, or to get some sort of reward.
In the first category, it makes no sense for people to evaluate what AI has done (a pure art evaluation would likely not be a game jam or it would be a specific one).
In the second, it's like a photography competition, of course, you can either generate or edit a perfect image, however it misses the point of it being about showing the most skill / the actual photo taking. Game competitions with mostly AI use would be more about the quality of workflows / prompting, which most likely has it's own jams and/or similar events.