They probably figured the guy (or his insurance company) would try to settle quickly, and they'd get to grab some cash. I'm sure they didn't expect him to fight the lawsuit and file a counter-suit as well. Chances are, the family of the dead perp has little or no money, so the counter-suit is unlikely to actually get Rose any compensation for legal expenses, let alone anything else. But, if he wins in both cases, at least it will prevent the perps family from ever being able to sue him again.
One question I'd like the perps family to answer is, how was he supposed to render assistance if the perp and his accomplice flee the scene? If the dead guy had collapsed inside or right outside the motor home, and his buddies took off, then it might have been possible to render assistance, but not in this case.