lookin-down, don't be so quick to think a booting like this equates to a "new rule" . As you can see from the OP's text, it appears that the *only* reason the cops came, was d/t some busy-bodies call. And perhaps those cops were just duty-bound to satisfy the griper.
I've had situations like that, where ..... I've just treated them as "isolated incidents" (barring an actual rule that REALLY said "no metal detectors".) And just given that singlular park or school a rest, and just gone back later. I have lots of parks like that, where I can detect till I'm blue in the face, yet....... someone way-back-when, whether me, or someone else, had at one time "gotten the boot". So you can see, that a mere "booting" does NOT necessarily constitute a "law" or a "rule".
I am reminded of a humorous incident where an md'r got booted from a school, in the late 1960s, in a city near me. An irate janitor had come out to boot him. The humble and apologetic md'rs says "
uh, ok, how about the school down the street?" The janitor says
"not there either". So the dejected md'r says: "
ok then, how about the park downtown?" At this point, the janitor was becoming peeved at the questions, so he just made matters simple for the MD'r: "
no metal detecting at any school or park in this town. It's not allowed".
The md'r left, with his tail between his legs

He proceeded to pass on word to other md'rs in my area, during the 1970s, that "
such & such town is entirely off-limits". I remember hearing that, when I was a new md'r. And "who was I to question my mentors?". But as the 1980s wore on, there were a few parks in that town that started producing barbers and such. So some friends and I would start making the trek to this town to md. Still though, in the back of my mind, I could still recall the warning that this "town was off-limits". Yet ... I never knew why, except that so & so said so.
So one day, in the 1990s, I ran into this old friend, and asked him: "who told you such & such town was off-limits?". He thought for a few minutes, and recalled that it was his older brother who'd told him that. So I said,
"well who told him that?" He didn't know. So ... the matter was dropped. However, a few years after that, I had the opportunity to be detecting with that brother. So I asked him:
"your brother says you told him that such & such town was off-limits. Who told you that?". He had to think for a minute, because, by now, it was 25 or so years later! Finally he remember, that his older brother had told him! (the oldest of 3 brothers). So I said,
OK THEN, WHO TOLD HIM that it was "off-limits"? And it was then that he recounted that the older brother had been booted, and warned, etc... And had thus "promptly put out the information to other md'rs".
Thus you can see, isolated bootings do not necessarily equate to "law". Now sure, if you go "get it clarified" and "get the booting over-turned", then sure, you can MAKE them cause it to be official. But is that a wise idea?