This is not the first time. People have been ousted just for speaking in Arabic. But in this case, the situation was handle unprofessionally. Seriously though, what safety issue?
Here is a video giving a full explaination of the incident. Even the other passengers was puzzled, and was asking why, explained by CAIR Chicago.
CAIR-Chicago press conference video: https://www.facebook.com/cairchicago/videos/10154828978329782/
Footage of the incident on the plane: https://www.youtube.com/watch?v=xNYMt4LKn3I