Dnd and Restraint?

This week, at our weekly game, I tried to start a bar fight with my players.  A troll named Brugg is the city enforcer.  He came into the inn they were at, shook down the inn keep for protection money, and then started playing grab-butt with the often intimidating tiefling warlord.  Wouldn't you know, of all the times to show restraint, this was it.  Not when they talk to city officials, not when they talk to city watch, not even when they talk to the inn keep giving them free room and board.  Nooooo, they show restraint with the enforcer troll who I am trying to use as an instigator.  She flirted with him, played along, and wrapped her tiefling tail around him in an oh so ticklish way..  When he pushed things too far and wouldn't help  with their questions, the players still kept things on the down-low.  Brugg left the bar (after a quiet dagger was placed at his nads) confused, pissed, and promising retribution.  Oh well, I will trade a bar fight for a recurring villain.