Besides why didn't you go for a lawsuit? They threatened and harassed you. They threatened your employment, your livelihood.
Not to mention you claim to be a security researcher and the first thing on your mind wasn't to record them and take down their details to publish later on internet. It's a good punishment. It would prevent those who visits you to do certain work and with their face and name everyone will know what they are, where they live. In case people want to visit and leave some very justified feedback about the FBI. It's perfectly legal to record them since they entered your home/property. Always, always record!
I bet they left a card so you could contact them. Even publishing that alone is good.
FBI is very afraid of the public light because of this in my opinion illegal stuff they do. FBI must have positive PR. Bad PR means less trust, less informants, etc.
A a security researcher you are supposed to know this stuff. How to deal with FBI, etc. I'm disappointed.