I work for an insurance company and I know you can sue for any reason. Just because the court ruled the suit can go forward does not mean anything beyond the fact that both side will be allowed to present their evidence before the court/jury makes a decision.
In an insurance law situation, I’d say the Good Samaritan only has to prove that a “reasonable person” would have reacted in a similar matter.
I’ve been unlucky enough to have stopped at numerous accidents. So many in fact that I’ve went back and taken first aid and CPR training beyond what I received in Health class and the Boy Scouts. The Texas law only states you have to stop and render only the aid you have the ability to administer. Depending on your training, that can be as little as phoning the police and waiting for the emergency personal to arrive.
Even if you only stop, phone the police and talk to the victim it can still make the difference between life and death. The phone call alerts emergency personal, the staying at the scene makes it easier for the emergency personal to find the location (in cases where the vehicle has left the pavement) and the talking to the victim may keep them from going into shock.
On a personal note, even though they are terrible memories, ones that I hope never to repeat, I’m proud of the fact that I’ve stopped at the scene of accidents. Even in the case where all I could do was hold their hand and watch them die, at least they did not die alone.