Do you think that, in his anger Alec was purposely using an expletive that was homophobic? He could have just as easily called the man a piece of shit or an asshole which would have not targeted any specific group of people.
When people grow up they are surrounded and influenced by the words of their peers. In high school and through adulthood especially in New York, swearing is nothing to blush at. While the literal meanings of those words are slurs, the intent of the person saying them shouldn't automatically be assumed to be racist, homophobic or sexist when the expletive itself was likely the result of muscle memory and the general vocabulary of their upbringing.
Not sure why I'm defending a celebrity on here, but I guess my consensus is that people are too fucking sensitive.