I don't see anywhere that it says he was removed for praying. He could have been reading the phone book for two minutes and theoretically the same series of actions would have followed.

A more accurate title to this thread would be "United kicks off a man for disobeying the instructions of the flight crew".

That being said, it's possible the United crew was hasty and overzealous. It's not entirely clear from the limited evidence in the article.