It really depends on whether people use "remaster" in its original guise or whether they use it as marketing speak, which is a much newer thing. PS2 games on the PS4 are remastered even though they aren't remastered in the traditional sense of the older PlayStation remasters. I imagine that
thelastword was referring to that type of branded remaster when asking the question.
For something to be classed as a remaster It simply needs to use some or all of the original content and "enhance" it in some way. Here they render what was originally on the PS2 but at the 896p mark, then upscale it to 1080p and add anti-aliasing with the frame rate being also being smoother in some games.
Although it's not a descriptor that I'd use for these things, even without the all the real-time graphical enhancements that are applied to the code and only having trophy support as an enhancement would still see the titles fitting under the remaster heading. I'm not sure anybody would really apply that to a game that only added trophy support though, even though it would be entirely accurate to do so.