First, this is an interesting thread concerning important issues. The last thread got closed down when it diverged from those issues.
As BIK_116.80 just posted, Reuters has reported the agent's name. You can google his home address and home purchase price if you are interested. It is beyond belief that a Secret Service agent in his right mind would invite such publicity or that the Secret Service would tolerate such notoriety. (It may be that the press does not yet have the name correct but sooner or later it will.)
So far the major print media has been pretty even-handed. Television will be another matter and the mess has spilled over. Good Morning America (ABC) interviewed one of the agent's lawyers and a passenger who supports the agent's story. The passenger more or less said that the F/A searched the man's belongings without permission when he left the plane. The passenger denied that the agent lost his cool. The segment also showed a clip of the President uttering his famous "madder than heck" words. AA's side of the story was limited to a printed policy statement that was shown on screen. In the print media the agent's lawyer was quoted that "It was the pilot who was rude, unprofessional and demeaning." The passenger was not asked to comment on that statement.
I have had the opportunity to observe the legalities of some employment issues and it is my impression that it is not so important that an action is justified as it is that the action is carried out no differently than in prior situations. Any singularities are legal red flags. Consider the Captain's statement "when the individual came back it was determined that he was in fact our 'armed passenger'. I then decided to stop my pre-flt and review the AA E2." This does not appear to have been a standard inspection of paperwork. Later in the report the Captain justifies his suspicions by saying that the F/As (plural) brought to his attention "what appeared to be strange behavior." Up to this point the concerns of only one F/A was mentioned in the report. The only behavior that was mentioned was that the agent left the a/c asking that the flight not depart without him. If white businessmen ever do the same thing without causing alarm then the term "strange behavior" will be questioned.
The first comments by the AA spokesman indicated that verification of the identity of the agent was the issue. Today's AA statement indicated that the demeanor of the agent was the issue. If there is any discrepancy in the stated reasons (and it may be that the two statements were excerpted) a lawyer will argue "pretext." John Relman is one of the most famous civil rights lawyers.
I think that the Captain did the right thing. I am not playing devil's advocate either. But I have seen lawyers at work and unless the police officer in the report corroborates the Captain's version this is not going to be a slam-dunk for AA.