When you see images on Google Image search you get an attribution - that seems the only difference legally between displaying the results of a db query for @HistoryPics twitter posts and displaying the results of a db query for "historic images" (say) on a search engines image search. Sure, the former has been more curated than the latter but having robots do your bidding doesn't appear in TRIPs agreements AFAIR.
When you see images on Google Image search you get an attribution - that seems the only difference legally between displaying the results of a db query for @HistoryPics twitter posts and displaying the results of a db query for "historic images" (say) on a search engines image search. Sure, the former has been more curated than the latter but having robots do your bidding doesn't appear in TRIPs agreements AFAIR.