I think one of the reasons why there is a lack of knowledge about suppressors in general is suppressors are known to most people as "silencers". In other worlds something only used in war and action films (or for real). By soldiers, spies and assassins. So most people assume suppressors are illegal.
And as some of you mentioned they ARE illegal in some states still. Anti-gun people are already afraid of people with guns. To know some gun owners can legally own and use suppressors...heh...
On the other hand, as much as I'm for legalizing legitimate ownership/use in Canada, I can see where the liberal party (and similar types) are coming from. In our major cities, like in any major city, we have our share of gun related crimes. Home invasions targeting gun owners. Putting more guns on the streets. If they can minimize the chances of seeing suppressors added to the list...
In the end, if Canadians want to have the same rights as many American gun owners...we'll have to move to the state with the degree of freedom we're looking for.