LLMs are by nature probabilistic, which is why they work reasonably well for "imprecise" domains like natural language processing. Expecting one to do decompilation, or disassembly for that matter, is IMHO very much a "wrong tool for the job" --- but perhaps it's just an exploratory exercise for the "just use an LLM" meme that seems to be a common trend these days.

The bigger argument against the effectiveness of this approach is that existing decompilers can already do a much better job with far less processing power.