You don't agree only because you've not read up on the issue (which is a little disingenuous). It's very easy and 100% clear:
I snipped the rest of your post simply to save space.
My reply was intended for me to better understand your position. While it wasn't meant to be argumentative, I do strongly disagree with your conclusions. I was already familiar with Causby. Not sure how you could accuse me of being disingenuous (which would not apply whether or not I knew anything about Causby).
The link you provide to Causby is a wiki page. Even working with the premise that Wiki is correct and not omitting some important facts, you seem to be misreading.
Look at the main quote in that article:
Thus, a landowner "owns at least as much of the space above the ground as he can occupy or use in connection with the land," and invasions of that airspace "are in the same category as invasions of the surface."
This clearly indicates that the landowner OWNS some amount of airspace above his land. It also states that a trespass in that airspace is the same at trespass on the ground. SCotUS decisions trump FAA assertions. That alone would give local law enforcement the authority and power to enforce trespass laws for a craft flying onto someone's property.
Same would hold true for violation of privacy or endangerment or harassment. Just because you are a few inches off the ground does not give you a loophole to skirt the law.
Remember that the court found in favor of Causby in that case... the US Government lost. (Although the full decision did give contravene the previous common law principle and give the government authority over "navigable" airspace.)
Further:
Since the aircraft passing over Cause's property were at 83 feet, the court determined the flight path was an
easement, a form of property right. Because the government had taken the easement through private property, Causby was owed compensation under the Takings Clause.
You mentioned earlier that no one owns the airspace over their property, they only have an easement. Again, I think you misread. Based on the above quote, the opposite is the case. The property owner in Causby was determined to have owned the space above his property. It was the government that had taken that easement and thus owed compensation to Causby.
It has been a long established principle (well before Causby, going back to English Common Law) that you own the airspace above your property. Prior to aviation, height of that owned airspace was effectively infinite. Causby put a limit on that. Even though the number used in Causby was 83 feet, the actual height you own was determined to be "as much of the space above the ground as he can occupy or use in connection with the land." That gave the courts discretion... the farmer in Kansas (flat land/plains) is going to have a lower "usable" space than the builder of a skyscraper in NYC (where, incidentally air rights are regularly bought/sold by builders and landowners without any FAA involvement).
Regarding privacy and photos, I also believe you have a misunderstanding of the laws involved. In public, people generally do not have an expectation of privacy. If you leave your drapes open and do something in front of your picture window, you would have a hard time arguing you have an expectation of privacy.
If, however, you build a high "privacy" fence or take other actions to shield your yard from public view, you would have a reasonable expectation of privacy. It wouldn't matter if someone climbed a tree, put a camera on a long stick to reach over your fence, or flew a UAV over your property... it is an invasion of privacy. To what degree you can can get in trouble will vary greatly on location and circumstance. The fact remains, however, that there is no exclusion for a UAV. The medium does not give you a free pass to skirt the law.
Another point which people often misunderstand... While you can take photo in a pubic place, how you use that photo can be limited. Public place or not, everyone still owns their own "likeness." You cannot use a photo of someone for commercial purposes without their permission. What constitutes "commercial" can be debated these days as technology has outpaced the law. If your YouTube video is monetized, it _may_ be considered commercial. You may need an attorney on retainer to find out for sure.
Again, I will not claim the officer in the the OP was correct. Nor will I claim he was wrong. It depends on the situation.
I will state that in SOME circumstances he could enforce a trespass (or privacy or endangerment) charge and confiscate the UAV as evidence. In the right situation, those actions would both be legal and could lead to a legitimate conviction. No FAA rule is necessary. The law is not regulating airspace - it is protecting private property and people's rights.
Another thing to keep in mind... if the police officer reasonably believes his actions are legal you can be charged with obstruction or resisting. Even if the original charge is dismissed or shown to be unenforceable, the obstruction/resisting charge could still be upheld.