Before we jump to conclusions, are we sure that the only thing this guy did was deny the holocaust? If it's just that, then it's a bit odd to say the least, but there likely is more to the story.
All signs point to us not having jumped to the wrong conclusion - he is indeed being jailed for simply having denied the holocaust.
The Supreme Court of Canada in 1991 made a decision saying that such an action would be unconstitutional. Note: he was deported for inciting hatred, not denying the holocaust. I am pretty certain that if I went out and denied the holocaust I would not be jailed.
I would also like to say that the US has a lot less freedom of speech than in Canada. I hear a lot about how religious Conservative groups are banning this that and the kitchen sink for promoting homosexuality. It may not be the government doing it but special interest groups sure are- and that does lead to government policy.
It should also be noted that Zundel was also arrested in the
United States in the past, he has links with
violent neo-nazi organizations and he wanted in Germany for hate crimes.