Spoiler
No, it wasn't pointless at all. They *never intended* to kill either them or the daughter. Moldava had one primary aim (getting the father, and getting out), and secondary aim (showing the daughter a little about how terrible her father was, which paid back in the final episode when she listened to her and believed her). Killing them, once they had their primary aim and just needed to escape would have instead made Lucy less trusting of her, and more likely to just free old dad at the end. The bombs going off was all about the distraction to allow them to escape the vault with minimal additional casualties.
Anyway, absolutely phenomenal show, best new show I've seen since Andor, and very close to being the best thing Prime has ever done (it's in joint second for me with The Boys, behind the Marvelous Mrs Maisel)
That explanation makes it sound even more pointless, Moldaver just came off looking like an incompetent murderer instead of a murderer. They didn't really need a distraction since the vaultdwellers were harmless and they had the overseer as a hostage.
It's not exactly a dealbreaker, just a little moment that felt like a dodgy rewrite or poor editing.