I think it's legit to have these discussions in open public forums. Sometimes compliance isn't cut and dried, or we're still just learning the ropes, and it's helpful to talk through our questions and thought processes. Plus, violators can screw it up for all of us.
In my experience, if we jumped through the hoops to get special approvals (like BVLOS, flying over people, flying at night, LAANC authorizations, etc), and someone asks, we take the time to tell them that because we want people to know we are complying with the rules and flying safely and legally. Public perception matters and can influence rulemaking. It's not always convenient, but that's not the point.
Personally though if someone tries to talk to me while I am flying solo, I'll generally tell them I would be happy to answer their questions after I land, but that I can't field questions during flights for safety reasons. Sometimes I even post a sign to this fact.
For me looking at this photo, there is no way to know if they have a VO. If they were in radio contact with a VO to maintain constant communication, a VO could be stationed at another location in the survey area in order to maintain unaided line of sight when the drone passes out of the RPIC's direct line of vision or to watch for other safety issues in the intended flight zone. For example, I've had VOs on the other side of a river from when I was flying 1) so they could alert me to hikers passing through that part of the survey zone so I could avoid flying over them, and 2) to respond quickly if there was a malfunction and the aircraft went down on that side of the river; someone walking up to me would have been unlikely to see that VO or know they were involved in drone operations.
So far I never have never called the cops on someone, and I see people violating basic 107 rules all the time in the SF Bay Area. I asked Oakland PD about this once at a street festival where there were phantoms hovering directly over large crowds, and they claimed it was a "grey area" about whether it was allowed -- in other words, they don't care because they have bigger issues to deal with. But if I thought someone's activities posed an immediate threat to people or wildlife, I would call local law enforcement.
And people do call the cops about drones. I fly in different places around the US, and in some places we contact the local law enforcement in advance just as a courtesy in case they get any calls. Some don't care, others have asked us to call them with daily updates so that they know what's going and can better field public calls.