If a villain is going to destroy a star, then destroying a moon to prevent it can seem like a good idea.
Give your villains big plans, grandiose plans, that will cause enormous destruction. Then have the obvious solution involve destroying something else - something a bit smaller, but still something that no sane person would really want to destroy. In other words, to save the world, the heroes have to sacrifice something. And not something easy - make it something that really hurts.
Make it almost bad enough that they question the very idea of saving the world.
Maybe they won't save the world. And that's a story and an adventure in itself.
Commentary by memnarch (who has not seen the movie)
I have been reminded that refueling is actually a thing in Star Wars, showing up both here and here, and seemingly here as a part of the whole lift-off sequence that didn't make it into the comic. I definitely need to reread this Episode soonish; I'm forgetting details like that from near the start of the movie. So thinking about it more now, using the star as a refueling source would make a lot more sense in the movie than trying for a time travel set-up, even if that would be a likely reason for people to dislike Episode IX. So in that case, the NPC giving Wedge's report is probably a nod to the actual movie plot while we're going to do a time travel shooting thing in the comic.
Also, wow that's a heck of a difference in size! I think that's the first, smaller Death Star on display since it's a full sphere, but still! You could almost drop it into the Peace Moon's trench! I bet we'll still have a trench run equivalent though to destroy it in the end, even with the new hyperdrive modulator. We had the original run, then the under construction run; I can't wait to see what we'll have for the Peace Moon. Through snow-covered mountains and machinery perhaps?
So will Jim finally get to pull off a sacrifice play? Maybe it'll be something like Independence Day, but with Han jumping the Millennium Falcon into the shield generator to let the rest of the Resistance in for an attack. It'd be a minor shame to lose the modulator that way, but that's the way plot devices go sometimes, especially when a former main character is involved. Maybe not crazy enough for a plan by Zeppo, but I can see that as a decent way for Han to die in the movie.
Admiral Statura: Wedge has sent a scouting report from the Endor system. The Peace Moon is... sucking in the energy of the sun?
Finn: They’re recharging for another shot!
Admiral Ackbar: Bootstrapping the weapon. Hmmm.
Allan: No. They’re going to destroy the star. We need to destroy the Moon.
Admiral Statura: Wedge says they seem to heave learnt the lesson from the loss of the previous defence station. A force shield is being generated from on the moon itself.
C-3PO: So there’s no way in to disable the shield?
Finn: There must be some way.
BB-8: What about the hyperdrive modulator? It lets us enter and stay in hyperspace when obstructed by massive objects.
Zeppo: Yeah! I’ve got an idea!
Chewbacca: Go on...
Zeppo: It’s incredibly dangerous. Perhaps suicidal. I could save the Resistance in a single spectacular blaze of glory!
Chewbacca: Stop tempting me to let you do it and explain.