I’m a current airline Captain and twice I’ve removed passengers for dropping the F-Bomb, while boarding. This is not a First Amendment anything. Without too much stretching of the definition of security and safety, anybody who demonstrates such a complete LACK of self-control in a public space, particularly a cramped, crowded and confined one, presents a potential security threat to my fellow crewmembers and passengers.
Any passenger who cannot restrain themselves well enough to NOT use profanity in an audible or threatening manner has no business being on an airplane. For the most part, most passengers are doing their best to mind their manners under very trying circumstances.