Well that's interesting! I've never heard of that before. Quite strange. I mean, then by definition, picking your nose in public, or whistling dixie while walking down Main St, is "illegal", because it's not addressed.
Something tells me this type of verbage is to cover things people actually care about, which ........ even you and I would agree, is good reason for the law, to stop endless debates of semantics, for when someone is doing something that truly requires on-the-spot interpretation of laws. So the truth of the matter is, no one cares if you walk down the street whistling dixie (even if not expressly allowed, or prohibited), right?? It's only if "someone cares" (ie.: a complaint is generated, because you're endangering people with your activity, or destroying things, etc....) is when judges might use such "catch all" clauses, just to put an end to semantics, when it is truly merited.
So I bet that:
a) the average person md'ing in your town, will likely be ignored (assuming you're not being a nuisance in some other way, leaving holes, sticking out like a sore thumb begging for attention, etc...). So odds are, this has no bearing on you. Or:
b) the average beat cop, gardener, etc... has no knowledge of the verbage you point out. And even if they DID, they too would know it's silly (lest why aren't they arresting dixie whistlers?). I mean, sure, if someone griped, and sure, if the cop ushered you on, so what? If you say "but it's not dis-allowed in all the city laws I studied in-depth", I HIGHLY doubt he's going to cite the passage you found. Instead, he's going to say that you are, in fact, violating specific things like "damage and destruction" type clauses, before he EVER cites the "silence on issues" clauses. Trust me on this.
So your "silence on issues" clause will never be the reason (if it ever came down to it, but I doubt it ever will advance this far) for a booting. Instead, they will morph something else to apply to you, that has something specific (ie.: non-silent) written about it.
And if you're afraid of those specific clauses *might* be applied to you, then you might have chosen the wrong hobby. Or you need to only look for items you can pick up off the top of the ground. Thus, the solution: keep a low profile, and avoid busy body kill-joys, to begin with. Go at low traffic times, don't stick out, etc.... Set your alarm for 5am Sat, and get a few hours in then. Just like nose-picking: no one cares, as long as you're discreet.