I have never backed away from pulling someone out due to liability concerns.
My process is to evaluate the situation for the following,
First, is there even a chance I can pull them out?
Second, can I do it without risk of injury to them or me?
Third, can I do it with minimal risk of property damage?
If the situation passes those tests then I will hook onto them but I will also give them instructions on what I want them to do. If they don't do what I ask I will reinstruct. If they still don't do what I ask then I just unhook and leave. I can only think of three I have left over the years.
Funny story, years ago I come across a guy stuck on the side of the county road. I pulled up so I could hook onto his blazer, I had a bronco. I hooked up, told him to leave his vehicle in neutral, I will just pull him out. I start pulling, in the mirror I see his tires spinning so I stop. I go talk to him, tell him to leave it in neutral, he says there is on way my bronco will pull him out. I just smiled and said, Yup, you are absolutely right, then I unhooked from him and drove away.