Department of Justice Canada's Internet site
www.justice.gc.ca
the government has a duty to protect the people from harm, that duty should supersede your individual rights.
you`re still free to leave the country and come back. but by doing so you've acknowledged that there is risk in travelling while the rest of the world grapples with what we're trying to deal with in our own backyard. And as such your 'rights' are reduced until you are deemed to not pose a threat to the rest of us.
i get their angle, but i don't agree. the good of all has to trump the good of one.
EDIT: most arguments I've read so far say it's cruel and unusual punishment, i don't see what judge will support this.