There is a big difference between an explanation and an excuse.

The sun in his eyes explains why the driver didn't see the cyclist, but that's not an excuse. The remedy when the sun blinds you is to slow to the limits of vision, or stop.

In some cases of intermittent sun blindness, we might proceed straight ahead based on having "memorized" the road ahead for a hundred yards or so, and bridge through the blind gap (we all do this whether we admit it or not), but that wouldn't cover making a left turn.

Sun blind or not, it's a straight forward case of failure to yield (with explanation) and the cop and the car's owner are responsible. It doesn't matter what he hit: pedestrian, bike, car, truck or telephone pole, or why he hit it, it's still the driver's fault. I expect that the city or their insurers will we stepping up and settling this (though who knows how hard they'll try to whittle any claim down).