[user104658]

I'm sure lots of people pray when they get on a flight, it's just not quite so overt. Assuming they're praying because they're planning a terrorist attack is perhaps an understandable human reaction - but it's still essentially racist.

FWIW of course as always I think it's all a bit silly, talking to imaginary people in the sky like it means something, BUT people are and should be free to do what they want so long as it isn't clearly harming or disrupting others.