Kidnapping robots are not exploiting any rules.
Many robots can not disengage in a pushing war.
However, I completely agree that a ball grabber can always try to outmaneuver a robot that may unintentionally damage it due to contact. This ALSO applies to the same robot when presented with a risk of being kidnapped. You have the same defense.
Again, many robots nearly tipped over at some of the regionals I've seen, and I believe the damage sustained if that were to occur would greatly exceed the damage being discussed here.
In last year's cooperative game, we went to an off-season competition in which there was an all-girls event. During this event, our robot became intertwined with one of our partners and a number of pneumatics hoses were ripped apart. It happens. We repaired our robot and continued to compete. At the very least, give these robots a chance to demonstrate the care they have taken in their design before whining about how they're going to rip your robot to pieces.