IMO, the perspective of the FBI/CIA is like this:
If the Earth had been as heavily populated in the time of the Romans, then they would have murdered more people than Hitler too – and perhaps they even did, because they were around a lot longer. If the Romans possessed covert technologies like the CIA/FBI, they would have used those. Roman society was not equal – they were emperors and slaves. It was good to be an emperor or a Senator and shitty to be a slave. The leaders of the CIA/FBI admire the Romans and like to see themselves as successful emperors/senators. It’s up to other people to stop them from being the “greatest” empire in history and killing the most people. Get in their way and you die.
I feel that basically all decent people are in their way, so they might as well make a good fight out of it.