The fact that the piece of legislation even exists is the weird part. The government doesn't get involved with anything of the sort for anyone else.
Same thing with questioning anything about the holocaust; it'll get you landed in jail but people deny elements of slavery all the time.
I'm not saying denying holocaust or slavery is good, but there is definitely a double-standard.
Denying the holocaust is not illegal in the US, or, as far as I know, in Canada. There is no similar law about other countries because there is no perception that people are trying to boycott any other country because of it's race or religion. And regardless of what the BDS crowd say about human rights, they're mostly a bunch of Jew haters.