Urgrim has M4, he just doesn't have Flee! as a talent, so while he can't beat a human he can keep pace with most of them. Since Sieghard is not attempting to break through the lines to us, I would agree that it's prudent to tactically consolidate to the rear.

At work at the moment but IIRC Disengage is a Full Action? I'll do that this round on Urgrim's turn. He'll back away from the semicircle of pikes, shield still raised, if he hasn't been egregiously run through by then.