This has been a poorly handled situation by the authorities. I work just down the road at another Police Asu involved in this job. Let me throw a possible theory into the equation, this is my opinion only, not based on any fact. A few years ago, a certain president visited N Ireland with a small army of agents and security. This was MASSIVE and all before the current increased threat to US officials. In one incident, a SS agent stepped out onto an active runway with a commercial jet coming in to land at Belfast. He was uncertain if his 'principal' was far enough away, so he held up his hand to the jet and called into his radio 'send that plane away'. The jet went round!! My question: What would have happened if it continued??
The USSS are (rightly) terrified of an attack on a government official. They don't request TRAs, they TELL people what they will have. If they arrive and are not happy with arrangements, they will not mess around with talks, they will suggest that they may deal with it themselves. Heavy handed, maybe, but they look after their own. Although you probably had the right to fly, you did the absolute right thing by going to the pub.
As an aside, in the future give us a call or arrange a visit if you have any police v aviation problems. We often have disagreements with the bosses as well, so we know the correct people to talk to. At worst, you will get a free cup of coffee.