But in this case real corruption would be a former employee of theirs regularly bending the rules for them. If no one else was chronically a day late and dollar short and expecting accommodation and understanding for it, telling them "no" and expecting them to actually comply with the rules is called professional ethics not corruption.
Lots of shitty people get away with their shit by counting on other people being "nice" and honorable no matter how badly they themselves behave. That's actual corruption and such people often want to argue that not going along with their garbage is somehow you doing something wrong when, in fact, going along with their expectation of special dispensation in the name of "niceness" is the bad thing.
Giggling at their crap biting them in the ass because someone is actually enforcing the rules for once instead of rewarding their manipulative BS is not corruption. It's schadenfreude.
People who are used to doing the right thing even when it pains them very much are not bad people for getting a small thrill out of karma being a bitch to chronic assholes who think the rules don't apply to them.
I don't know if this was an instance of corruption or not. Neither do you. The devil is in the details and neither of us knows all of the details.
But, no, "clearly and obviously corruption" is not true. There are other possible explanations.
Having dealt with asshole customers who wanted the moon when the rules explicitly forbade that, I can well imagine this was only schadenfreude and he didn't know how to clearly explain that when he told the anecdote years after the fact to a group of friends.
Do you really think "good government" means someone staying late and doing work off the clock because their jackass former employer is showing up again just as the place is being locked up? If they weren't routinely a minute too late, this wouldn't have cost them anything on the order of the amount of money they screwed him out of.
I don't think such accommodation would constitute good government. The fact that being held to the rules was a constant source of friction that cost them royally implicitly suggests they didn't play by the rules. It implicitly suggests they routinely and regularly were late and their paperwork was botched and they expected to simply get away with it.
Being screwed by them wrt the bonus money may have protected him from stupidly "being nice" to them and thereby ending up on legal charges for corruption. That is often a slippery slope where "just this once because we are friends" becomes "in for a penny, in for a pound" and you don't know how to back out of it without being burned.