alt Hacker NewsIn proper English usage it would only be a bigoted
(obstinately or unreasonably attached to a belief, opinion, or faction, in particular prejudiced against or antagonistic towards a person or people on the basis of their membership of a particular group)
The Rehat Maryada would suggest that is in no way whatsoever an unreasonable suspicion.
Sure, your manager likely didn't carry one on airplanes .. but that still falls short of being an unreasonable check.
As a white guy who was caught accidentally carrying a large knife once through security, at the bottom of a carry-on backpack I'd had since high school, I don't think it's in any way essential to use racial or ethnic markers to figure out whether someone is taking something dangerous onto a plane. I didn't even know I was trying to bring a knife onto a plane at a regional airport. There's no reason to think that Sikhs are explicitly going out of their way to hide something.