That sounds like a problem with police procedures and accountability. It's weird to blame potential victims for that.
And in this case, notifying the police would have seemingly affected the test. Based on the reaction they did have, I would guess such notification would have resulted in the police doing many more drive-bys of the courthouse and generally being alert.
> "That sounds like a problem with police procedures and accountability"
It would be supremely stupid to not plan and account for these kind of systemic social problems when you're planning out your contract to break into a building. "But they're the ones who suck, I did nothing wrong" won't bring you back from the dead.