• They asked for belt extensions despite not actually needing them, and didn't use them anyway, giving rise to the possibility of using them as weapons (albeit awkward ones)


• Positioning themselves around the plane in a pattern mimicking the 9-11 hijackers


• Flying on one-way tickets


• Flying with no checked baggage

None of which is illegal, but all of which together is reminiscent of preparing for a terrorist attack.  So long as airlines are erring on the side of caution, that's a good enough reason to remove somebody from a flight.  And if they refused to leave, that's a good enough reason to take them off in handcuffs.

Now, that argument is based on the woefully shaky premise of uncritically accepting all the various rumors floating around.  But support for the Imams seems to be based on uncritically accepting the Imams' explanations.

First-hand account here:

(disclaimer, I think the site is in cahoots with those rascals at "faux news")

Other Muslim passengers were left undisturbed and later joined in a round of applause for the U.S. Airways crew

Another passenger, not the note writer, was an Arabic speaker sitting near two of the imams in the plane's tail. That passenger pulled a flight attendant aside, and in a whisper, translated what the men were saying. They were invoking "bin Laden" and condemning America for "killing Saddam," according to police reports.