paradis only knows of humanity vs the titans, if you rewatch the show youll notice that theres a motivational speech about how fighting is humanitys only hope every other episode, and it makes sense from their perspective, they in fact do need the motivation every time a hundred soldiers has to throw their life away to achieve some goal and its really hard to say the motivation is misguided when to their knowledge they are all that exists of humanity and everything that opposes them is not human and permissible to kill, this means that when theyre faced with other actual countries with real people it becomes very very easy to justify killing them, even though the situation has definitely changed
though this sentiment does also extend to outside the show, a large portion of the viewers DO side with the yeagerists and see the genocide as being fully justified, if you look at youtube comments talking about the genocide being justified theyll literally say something like "those that side with paradis are those that heard erwins speech", and thats literal war propaganda in action breaching through the 4th wall and directly influencing the viewers, so when you say "well being pro rumbling here is just demonstrably evil and irredeemable" while i think to a certain extent youre absolutely right, i also think you also arent really engaging with the media in the way it was intended, the pro rumbling side is meant to be an understandable position to take, even if it is very much misguided and fueled by propaganda
also just as a side note i see a lot of people trying to claim that if erwin was alive he would side with eren, similarly a misguided take but in that particular case we literally see erwin greeting hange after she dies telling her what a good job she did at slowing down the rumbling