I would just let the player start up a new character, and not worry about the advances. 

Ah! Thanks for pointing that out.

Like Matt said, if they fight back, it's seize by force.  If they don't fight back but try to save themselves, it's going aggro, with suck it up and give in collapsing into one outcome, harm.  If they can't do anything to save themselves, then the PC inflicts harm without needing to roll.  That happened in our game last night: a PC wanted to shotgun blast an NPC who was completely distracted, so she did.  Boom, dead NPC. 

At the start of our first session, I offered a few very high level flavors of setting: a drowned world, a lush, poisonous world, a "typical" desert wasteland, etc., and let the players decide which one they were into.   

Sometimes my descriptions feels like the Barf Forth Minute, then we're back to the game.  Need to mix it in better.

A couple of the PCs are less tied-in than the others.  Makes me anxious, and want to start throwing ersatz crappy at them until an NPC sticks.

If the circumstances were right, I'd be tempted to ask for one main roll with help from the others, with everyone who helped getting the bonus for following the advice.  Has a certain cinematic field, with a gang using subtle signals like meaningful glances or muttered comments before the fireworks begin.  But it presupposes a point person, and a united front.

If they're truly separate actors in the situation, then they might be each other's biggest threats and best ways out.   "Popeye, Bluto's always had a soft spot for Olive.  Your best way out is to grab her and stick a gun to her head.  Olive, it wouldn't take much to provoke Bluto into a jealous rage against Popeye, which would give you a chance to slip out."