I used the Paladin deception option and it didn’t break my oath of devotion. I don’t know if other sorts of deception always do, or if it’s only when there is an (implied) promise that is then broken, if it’s consistent at all.

But I agree that it would seem appropriate to have a non-deception persuasion option to get the tieflings to leave, eg by convincing them Lae’zel wasn’t one of the githyanki who killed their scouts and you’ll make sure she doesn’t harm them.

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"