That was exactly the time and place. And rest assured, they would have still fired him no matter where and when he did it.
And tell me, what did he say that was wrong or embarrassing?
He said in other jurisdictions, he has seen officers bully and harrass people innocent of any crime. True.
He said officers have no duty to enforce any edict that clearly violates the constitution. Also true, and the Nuremberg 101.
And last, he said that the US Police are dwarfed by the US armed populace and should never forget that it would go badly for them if they ever lose that permissive trust we give them. He further said he has seen that in a war zone. Also provably true.
Emotion aside, what exactly did he say that is even slightly controversial or improper for any police department?
As has been reported. He could have said anything he wanted to but he was in uniform representing the office of security. All reports said he was factual but he should not have said it while in uniform and in an official vehicle.