From what I understand, none of the people involved here are originators of the idea that led to this solution. Not Buckmaster nor Alpöge nor OpenAI. All of the above were using LLMs to push other mathematicians' ideas forward (Diego Cordoba and Luis Martinez-Zoroa; named in the linked document).

I don't know how the math community handles this but normally I would think if X mathematician comes up with an idea and Y mathematician uses it to solve some problem, Y would get credit. But does that change if Y heavily relied on LLMs? I suppose we're going to find out.