Because it’s rather expensive and difficult for some random person to do human genome research from home, but anyone with the right knowledge and a laptop can still make significant progress in AI while sitting on their couch at home.
By your logic, if HGE is cheap and easy, then it doesn't make sense to ban it and we should just let people experiment with their to-be infants all the time. What are you gonna do? Ban something you can do with some test tubes and a needle?