Jesus christs steely, he settled to avoid a lawsuit... not to get a lighter sentence. The insurance company has no vested interest in whether or not Stallworth goes to jail. They do, however, care about continuing to pay attorney fees, and possibly being hit with a larger judgment. The fact that the family was taken care of is only a by product of standard procedure in cases like this. Florio likely had no knowledge of Stallworth's umbrella policy, or he would have known that it would have paid all costs above $300,000.
Plus, even IF stallworth paid anything, these settlements take into account someone's assets. So if it were you or me, we would have paid much less. It's on a sliding scale, so income is irrelevant.