The description of the ability specifically states that it will not cause a masquerade violation, however:
I used it, then fed from a bum in an ally in Santa Monica.
I left the alley and walked up to the guy you can threaten to get his watch/wallet. (I had already done so)
I hit E to speak with him, at which point he started running, and I got a masquerade violation.
I didn't have any other powers active.