so, why would trudeau support such a monstrous swindle as this?
well, he is a trust fund kid.
but, he governs on opinion polls, and opinion polls have consistently shown that canadians are indeed extremely confused about nafta, partly because the initial debate around it was so confusing.
the liberals tried to argue that they support free trade and oppose nafta (the correct position, fwiw), but the reality of the "free trade" part of nafta being an orwellian distraction never got through to canadians, who have always interpreted the north american "free trade" agreement as a free trade agreement - and believed that was a good idea. after all, it was designed as a legacy project for the elder trudeau, based on the reciprocity deals of his idol, laurier.
it's the liberal position on this that is consequently so disappointing. they came in with this list of demands that we haven't heard anything from since, while ignoring the parts of the deal they initially opposed - because they're morbidly afraid of getting lost in the same debate. but, they were right then, and now they have the data to prove it. instead, they're governing as conservatives, while paying lip service to ndp ideals.
people have accused the liberals of lacking principles for years. that is what their approach to this is really demonstrative of: they're more concerned about electoral politics than they are about good governance.
https://www.thestar.com/opinion/contributors/2018/06/18/should-canada-give-up-on-nafta-yes.html