"On it's own" generally means "not steered" or otherwise given professional guidance or input.
I would say "developed the necessary software for a simulator" to be even more impressive - "here solve this problem" and "OK, but first I have to built the entire lab!"
It can code enigma simulator from the algorithm. That's not really a problem. Astra will send computing to programs, LLMs are not good at computing themselves, why is this a big deal?
Well were they? Short of you showing us the answer just sitting there or some tool that can already solve it I see no reason to believe this was the case. And the problem being out there unsolved for a long time implies it's not the case.
And that's taking your concern at face value. It just seems incredibly pedantic to say it didn't solve the problem by itself because it created it's own tools to help solve it. Beyond that we could also fault it for not creating the GPU's it's running on.