As reported by Reddit. A Vulpera can cast Return to Camp (their second hearthstone) while mind controlled.
Although most racials and abilities are up for grabs by the computer AI when MCd, this should really be taken off the list. Astral Recall was removed for Shaman.
Considering the nature of the N’zoth fight and the fact he will perma mind control people, it’d suck if someone hearthed and missed their guild’s first kill.