It would be a flex to save the children personally afterwards.
I gotta say though, the plot moved a bit too fast for my taste. There was no evidence of a betrayal if the plan was just to lend the grail out, so Lucian immediately jumping to her side doesn't feel right.
They needed the demon king to out himself due to her interference before disappearing. And ideally, delay a night with him being imprisoned before showing the grail was fine so the conspirators couldn't talk their way out of it.