The crux of the case is there was a witness, walking his dog. So he became the 'persons'.
And it was his complaint and then his evidence that caused and then won the case. The fact that he was an ATPL IIRC probably means he knew his air law - whether that had any influence either way I do not know. It probably had some influence on his credibility, I do not know if his motivation was questioned.
Many strips suffer from the 'classic neighbour from hell'. It is simply necessary to understand what is legal and what is not and act accordingly.
The example of a shed - well it must be man made so keep 500' from it!
I'm not saying this is a good or in anyway sensible rule. Simply quoting a fairly old case which demonstrates the catches possible in rule 5 whilst doing something which seems very sensible.
The recent changes in training from unlicensed strips have introduced similar issues in terms of build-up areas.