I don't think identity politics had anything to do with it. Bernie Sanders was against the TPP as much as Trump was, for many of the same reasons.
This certainly isn't scientific at all but a quick search for tpp (all time popularity) shows the first page of results as posts that primarily took place more than a year ago. https://hn.algolia.com/?query=tpp&sort=byPopularity&prefix&p...
Trump mentioned he was opposed to the tpp almost exactly one year ago today.
If we search the popular 'tpp' posts from December 1st 2015 to today, we get results that show posts that are critical of the tpp but over half of the first page of results have less than 100 upvotes. https://hn.algolia.com/?query=tpp&sort=byPopularity&prefix&p...
Like I said, not scientific but kind of interesting I guess?
In other words, the same people who disliked TPP before could dislike it today, but not be commenting in the threads talking about Trump's opposition to it and new people who didn't comment on it before could be expressing their opinion formed by recent events (or even harbored from before).
I definitely think an in depth study on internet group think would be interesting, I just think that examining closer to see who composes the group and how it's thinking is an important aspect of that study.
Tesla is another great example. Ordinarily, self serving research by a corporation is dismissed as junk science or "misinformation." But let Tesla publish survey results [1] to argue their end of a regulatory dispute and that view ricochets around the progressive echo chamber as though a voice from the sky had spoken The Word, Tesla of course being the golden boy of anti-fossil fuel group thinkers.
The sudden concern for the consequences of stopping these big trade deals is nothing more than partisanship. Pretend otherwise if you wish, but it's dead either way and the world is better for it. Thank you President Elect Trump.
[1] http://venturebeat.com/2016/11/11/tesla-autopilot-germany/