Unfortunately, the answer to that last question is yes. Because Canada has not acted to protect his rights, his rights are going unprotected in the United States.
I don't know that I will venture an opinion on whether or not Canada has an international-law-based obligation to intervene. Certainly there is some authority, I think, in Canada, and certainly in the United Kingdom suits were brought against the British government by British detainees to enforce their rights or to compel the British government to enforce their rights. So there may be some authority in the common law tradition for requiring the Canadian government to intervene on his behalf.
But that shouldn't be necessary, because it's so obviously the right thing to do.
As for whether or not the Canadian government has assisted, what I will say is this. The Canadian government has taken the position that it wants Omar to receive a fair trial, yet the Canadian government has numerous documents in its possession related to his case and to his prosecution. These are documents that may replicate reports generated in 2002 by the U.S. government that have been lost or otherwise gone missing and that could provide an important source of evidence for his defence at trial; yet the Canadian government, notwithstanding its public protestations, has fought tooth and nail against the disclosure of those very documents that may help him in his defence. And so certainly the government's position on that issue has been somewhat inconsistent.