There's tradeoffs. If training LLMs (and similar systems that feed on pure physics data) can improve nuclear processes, then overall it could be a net benefit. Fusion energy research takes a huge amount of power to trigger every test ignition and we do them all the time, learning little by little.
The real question is if the LLMs are even capable of revealing those kinds of insights to us. If they are, nuclear is hardly the worst path to go down.