Can you stop three car lengths behind a car at a light in California?

Driving this afternoon, we came behind a car who was about three car lengths behind the car in front of him, which was waiting for the light to change. We don't know why he chose to stop so far behind, but it looked like he wanted to stop in the shade of the overpass. If we had hit him, would he be liable for contributing to the accident? Sure, you're not supposed to drive so fast you can't stop, but he was both in the shade and three car lengths behind where he could have stopped. No, we didn't hit him, but I thought it was wrong of him to jeopardize traffic like he did. ... Comments??