>Now whether they were watching your ex-roommates for a good reason is neither here nor there, but the fact remains that the FBI wouldn't be doing their jobs if they didn't keep tabs on you, someone whom they were living with.

This is patently untrue surveillance state propaganda. The job of law enforcement is not to prevent any crime from ever happening by following around potential criminals or associates of possible criminals. The fact that we're even OK with there being a watchlist at all is a bit disturbing to me.

No, that is actually the job of law enforcement. That is what Bruce Schneier means when he talks about good intelligence work and good law enforcement work as protection against terrorism, as opposed to security theatre.

Or, put another way: planning to commit a crime (criminal conspiracy) is itself a crime. Being a suspect of a crime is a valid reason for law enforcement to watch someone. Associating closely with someone who's part of a conspiracy could very reasonably put you under suspicion for being part of the conspiracy (although it's not evidence against you, of course).

Of course, the lines between when people are reasonably suspected of crimes has been moved far and fast in the wrong direction and needs to be pushed back.

Yes, but friend: it matters much whether the state's deployment of ethics in the selection of potential suspects are good and just. An individual's ethnic heritage and choice of religion cannot in a free society suffice for just cause in being warrantlessly surveilled. That's what warrant means.

How do you know that the roommates did not have reasonable suspicion and warrants on them.

We don't.

But the odds are good - based on hard evidence - that the absence of warrants and reasonable suspicions makes no difference whatsoever.

makes no difference to what - your not making sense here

You can just assume that most muslims in the US are on special watch lists.