Maybe I'm being picky or missing something, but doesn't the gaze of a vampire duplicate dominate person as opposed to dominate monster? If so, shouldn't a native outsider be immune to it?
In other words, in Drakthar's Way, shouldn't he have dominated the human sorcerer mercenary instead of the tiefling fighter (who's immune to effects specifically targetting humanoids?)
I think you're right. Time to wave the magic DM fingers and fix it.