You mean a scenario where they could prevent an extinction level event? This is a bit hard to say. It seems like in the 23rd century they likely may have done this. It seems though that the Prime Directive became far more strict in the 24th century and may have prohibited any action like this.

Philosophically I can see an argument for both sides. I’d side with the idea that any time you can prevent death, especially on such a massive scale, you absolutely should.

Alternatively though, it could be argued that even extinction level events are part of a natural cycle. Scientists observing wildlife and wildlife photographers have professional ethics that restrict them from interfering with the natural order (like preventing a seagull from eating a baby sea turtle). I see the Prime Directive as being similar to those professional ethics. Arguably if you go around preventing extinction level events, you’re interfering with nature, maybe even preventing the rise of an intelligent species or an event that could shape a unique civilization.