Whenever we (myself or my friends do a recovery of a stranger) we always get a phone video of them releasing all liability if things go to sideways. They understand they asked for help and we offered it, same goes for our rigs. Individuals are responsible for their rigs. PERIOD. Also be careful offering money, if he were to try and sue you the rules of proof are VERY different (at least in CA). Intent matters. You're offering money could be seen as acceptance of some responsibility and thus put you on the hook for some or all. Not likely but possible if he's a real piece of work. And even if he's wrong and law is not on his side, you still need to go defend yourself, just not worth it. Again, we would do the same here because, like you, I would probably offer to pay his gas or split the tow, but I would get a video of us agreeing this is not an admission of guilt or responsibility, just a charitable act. And we agree to go our separate ways after, end of it.
We might be over cautious but you never know when you'll get "that" guy. 30 seconds of video can save everyone a TON of headache later.