They way I understood the time-line, is that the "challenge to the officer" was BEFORE "informed". (ie.: before being shown any chapter & verse actual rule/law)
But I'm glad you have implicitly stated my case

That it's a case of "informed" vs "challenge" timing-issue. And BTW, to merely be told "scram" or "stop" is not to be "informed". No-more-so than if I walked up to you and said "jump", you might be inclined to say "why?" or "says who", rather than to jump-at-my-command.
And, let's just say that, yes, eventually (after back-up was called) the man eventually got some silly reference to depth of hole or "metal tool" rule shown. But , again, using the Candid camera example .... SO TOO were they shown a sign (albeit fake in that staged case) of the speed limit for walking (2 mph, or whatever). And guess what they did EVEN THOUGH SHOWN THE SIGN ? They kept saying things like "you have to be kidding?" and "how the h#@ is a person supposed to have known that?" Or "How am I supposed to know how fast I was walking?" and "you're not really going to write me a ticket are you ?"
Yes I know the candid camera stunt was staged and *obviously* fake. But put yourself in the shoes of the person being told "you can't dig sand castles". It's not a far stretch from the understandable reactions of persons being told you're walking too fast, I'm going to have to tell you to stand still and give you a ticket".