Looks like another case of children knowing best until they are "educated".
Note that religious knives are prohibited from airlines and appear on the list Pierre quoted, as are replicas which has been interpreted rather broadly. I've heard of miniatures and kirpans fused to the sheath being carried by Sikhs. I don't know if there are different branches of the religion that find them unacceptable.
I guess a legal difference may be that using the public transport system is "voluntary" but seeing that a child is educated is mandatory? (I'm guessing mandatory in Canada, too.) But a rental agreement is voluntary, and discrimination there isn't questioned to be wrong.
I'm sure a similar case will occur in the US.
As I've said before, in these times it seems that
"zero tolerance"= zero brains.