Artificial superintelligence is a specific thing that doesn't exist yet. A ban on it would be a cautionary measure in case of future advancements. A ban on artificial intelligence writ large would arguably ban my high school project that played Tic-Tac-Toe optimally.

It's probably important to note that ASI (and its more conservative form, artificial general intelligence or AGI) are goals, which is to say that they describe the result and not the technology used to get there. LLMs are a specific technology that I'm pretty convinced will never achieve AGI, let alone ASI. Specific-purpose AI has been around for decades (e.g. Deep Blue, which was world-class at chess in the '90s), and LLMs aren't really any different; their specific purpose is completing sentences, though, and that tricks a lot of people into thinking that they can actually perform metacognition in the way that an AGI would.