What would you define as a "democratic process"? It's a conference, not an election - the government is SUPPOSED to investigate different policy options in such conferences. It would be a failure of democracy if they weren't, in direct opposition to what you are saying.
Next time Harper goes to a G8 meeting should he bring along Joe and Jane Sixpack so the "democratic processes" can be honoured? It's the same thing - the "democracy" we live in means we elect a government, not that we directly participate in all its actions.
Did you know the USA has plans to invade Canada, plans that are periodically updated by their military planners? Oh noes, the USA is gonna invade - why else would they have such plans!
It is similarly ridiculous to assume that just because the government is exploring the possibilities of a NAU that they are intent on some kind of fascist coup where we all end up as drones working for the transnational corporatist elite. It simply does not logically follow, it is a typical conspiracy theory where facts are taken completely out of context and given interpretations that are more the expressions of paranoia than any even remotely probable truth.
As far as proof of the constitutional blocks to such a plan, see
here for Canada and note that any one of Quebec, Ontario, BC, two Prairie provinces, or two Maritime provinces can VETO any changes to the Constitution of Canada. So, even if somehow these shady characters managed to suborn Parliament to get their NAU into law, they would also have to convince all but two provinces to do the same. Provinces in which, by the way, this exact process (feds wanting to implement constitutional changes) failed in at least one previous occasion when issues that are not nearly as fundamental were at stake.
In the USA there is also a clearly defined protocol for amending the Constitution, which cannot just be ignored. You don't seem to understand that the legitimacy of these governments is entirely bound up in their Constitutions, and that these documents have real power that can't just be overridden by some committee without legal standing.
PS - I'm not saying there will never be an NAU, I am saying there are two paths to it: one, the countries involved go through legal processes (which include consultation with the people in democratic fashion) to make it happen; two, some kind of military coup or revolution replaces the legal governments with ones that have no roadblocks to forming such a union. In neither of those scenarios does it somehow happen under the table where you wake up one day and find out you are a citizen of the United States of North America.