I guess I wouldn’t be too talkative if a stranger came up and asked me what I was doing and if I had a waiver. Remember your waiver doesn’t mean you are the only one allowed to fly there.
As far as needing a waiver you are correct that what he said the operation is for would require a 107 license but that’s not clear to most people even people that understand the rules. Frankly I’m not sure the FAA is even all that clear on it. According to the FAAs user identification tool
User Identification Tool a reasonable person could come to the conclusion you wouldn’t need a 107 license for that operation as long as you answer yes to “are you flying for fun?” According to the FAAs own tool.
I know the FAA has said otherwise but it really is a bit of a grey area as far as the material they have available.
(Note: I’m not saying he wouldn’t need a 107. I think he does. What I am saying is it easy to see why people are confused about it. )
I think it’s just about educating people and asking nicely. You might be frustrated after following all the rules but if you take that frustration out on people who don’t understand where you are coming from then you just seem like a donkey to them and of course you aren’t gonna get cooperation.