Assuming the facts stated are true. A classic case for me of "I may disagree with what you say, but I will defend to the death your right to say it."
I will observe that:
(a) The right to wear offensive slogans (assuming the arabic on the t-shirt can reasonably be construed as "offensive") is a protected form of First Amendment expression. The classic case upheld the right of a person to where a t-shirt proclaiming "[expletive] the Draft" to a public courtroom in violation of the usual dress standards.
(b) Although JetBlue is a private company, it is regulated as a common carrier. While I am not familiar with the law governing air travel, it raises a profound question in my mind whether JetBlue or any other airline can refuse passage because they disagree with someone's t-shirt.
(c) The apparent active role of federal employees, operating under color of their federal authority in the course of their official duties, to deny this person his First Amendment right of self-expression, may give rise to a civil action against the employees and the United States.
OTOH, on the internet, no one knows if you are a dog. I will wait getting more angry until I see some other confirmation that the events described are real. Certainly a suifficient case has been alleged to warrant investigation by journalists, if not some competent federal or state authority.