Interesting. It's possible that smaller groups assaulted the Arena to find people but it doesn't really seem realistic. When the Tower was on fire, people were all gun-ho about jumping ship and leaving friends behind. I expect the same reaction out of an already demoralized group like ones left in the Other Tower. Datu's situation was unique because Angel and Riley knew he was alive and they were close enough to do something about it. They also were under the impression they'd just lost Michael so the idea of leaving Datu behind was out of the question at that point.