Pointless Ending Sequence, why take the kid?

After Sheryl saw the bikers, who treated her like crap, get wasted trying to kill Broker, what was the point in she grabbing the kid and getting Broker on her butt when she saw what he could do? As well as the police would be on her tail too. Up to that point, she and Gator could have just backpedaled away from the whole mess since they weren't in the shootout. But for the sake of a "Mel Gibson going bonkers to save his kid" sort of chase finale, they had both Sheryl and Gator needlessly messing with Broker's kid. The kid meant nothing but trouble for both of them. In no way could they benefit from it. But it is stupid action flick where the plot is all about creating more excuses for explosions, gun fire and chases.

What are they doing? Why do they come here?
Some kind of instinct, memory, what they used to do.