I have heard a couple stories like this now.
The few times I have encountered Local Cops, BLM Rangers, and Forest Service Rangers while shooting in Cali, they havent been sneaky at all. They just drive up and introduce themselves like you would expect.
We chat for awhile, I always ask for a business card so I can contact them with questions in the fuuture, and they go about their business.
Its a shame you didnt approach him directly and ask if he needed some sort of help. Something like: "Sir, we noticed you have been sitting there for awhile. Is your Jeep broke down? Can we give you a ride to town, want to borrow my cellphone? Oh, your cars fine and you have your own phone. Then what are you doing out here?"