don't think they ca sue in Canada.
Why not? Other countries value free speech as much as we do, and are fighting its abusers too. The legal system is wrestling with the specifics, but not the concept of cross-border (transnational) litigation. Plenty of examples out there.
The OSCE (Organization for Security and Co-operation in Europe) has published a detailed database on criminal and civil defamation provisions in 55 countries, including all European countries, all member countries of the Commonwealth of Independent States, the United States and Canada.
Canadian woman wins landmark lawsuit against Google Inc.
Canada: Libel and Slander Act, R.S.O. 1990, c.L.12, as amended.