Sorry, but I don’t think your facts are correct here, and I don’t get your reasoning.
They didn’t know he was compromised or that there was a super weapon until Lonni told him.
They could have had a deadman’s-switch self-destruct (as well as a booby trap for unauthorized access) rigged on the comms console. They could have had a backup escape vehicle, and at one point it sounded like they did when Luthen last met with Kleya, but then Kleya just goes and hides at the same safehouse (did they run out of money for new sets/locations?), and has to get Andor to rescue her?
They had immense resources and time to plan contingencies. Instead Luthen botches his cleanup and his suicide. It’s betrayal of the competency these characters had been established to have. Meero too. She does a silly villain monologue with an unsubdued and visibly armed Luthen.
They could have all flown out together immediately and went to Yavin, which is what Kleya ends up doing anyway. They could have brought in the equivalent of Kim Philby with firsthand knowledge to lend credibility to their intel. The only reason it didn’t go down that way is because they need to make it fit with Rogue One, and when Gilroy doesn’t know what to do with a character he kills them off in a kind of stupid avoidable way. It was Gilroy’s idea to kill off all the characters in Rogue One, btw.
Oh also Bix’s ending struck me as corny.
That does make sense. Thanks.