OP here. The purpose of the grabs that I was talking about was to stop someone from punching me. Was I sure if they didn't have a knife, no. After getting the arm the serious intent was to stop them from doing anything further by using them as a weapon and hurling them into objects.
Most muggers I've entertained can't punch worth a damn. Grabbing their arm and throwing them was an untrained, but effective response.
I was interested in that the usual roles of nage and uke are pretty well jumbled. The attacker really looks like they have the nage role here as far as using aikido goes.
I think there is a point when your training begins to revolve around transitioning roles between uke and nage. This would be kaishiwaza (reversals) or takemusu aiki - the continued interaction of partners. It's a bit of a shock because we become programmed early on: uke attacks like an idiot, nage throws uke. Then all of a sudden, we hit this "who says uke can't trash nage" thing and it is a shock. But it creates a more dynamic exchange between partners and expands the interaction to focus more on the connection and less on role play. It certainly changes things when uke is allowed to do something back to nage.