I just watched this one like a week ago. The first time they go there is because they just detected the shockwave from the explosion. Second time, there’s no explosion, they detect the civilization and say, nope don’t wanna deal with those pre-warpers.

As for the point of the episode? I dunno, felt like a time loop one that’s supposed to make you think (like cause and effect) but just so poorly executed that it was forgettable