Yep, lawsuits about this issue have been made employer responsibilities pretty clear. Freedom from being offended trumps free speech.
Yep it is ironic when a leftist concept, someone is responsible for someone else offending someone, ie employer is responsible for one employee offending another. It is however sad that the American principle of free speech might be the one that loses. Of course in this case:
1. There is no free speech issue, this is a matter of a private company not the government deciding appropriateness at its place of business.
2. I would hope the Airline is not reacting to the leftist harrassment threat, but I know better.