When you impose a punishment on one group that you don't impose on another, that's a form of discrimination. It's as simple as that. There is nothing about the group upon whom that special punishment is being imposed that is different in a relevant way. Yes, they're different because they're dual nationals, but that's not relevant to the alleged grounds upon which citizenship is being revoked. In that sense it's arbitrary, it's discriminatory, and it's a violation, in my respectful opinion, of the Canadian Charter of Rights and Freedoms.
On April 16th, 2013. See this statement in context.