In most cases these sudden restrictions are the result of somebody taking the micky. Because it is a civil matter, the airport has no (practical) sanction against that person/operator.
At Shoreham, we lost the out of hours concession because a certain outfit there was abusing it. The airport cannot do anything about them, cannot terminate the lease before it's up, and anyway needs the rental income, so we got the predictable kneejerk reaction.
And when anything like this happens, the H&S yellow-jacketed crowd get an immediate upper hand which they positively delight in using. These incidents are a godsend to them. If nothing bad happened they would be superfluous.
Same in an ISO9000 business. If somebody cocks up, the ISO9000 manager
ends up running the company - until the management wakes up and winds him back into his hole. But often the management doesn't wake up...