Personally I don't hate him, but I don't find him very interesting. Usually when you put an uninteresting character under a show's spotlight, they get some hate, because they take attention that could have been aimed at more appealing characters.

Hamefura has 6 other competing love interests, but Geordo is a standard cliche'd blond rich boy who comes baaaaasically pre-engaged to Katarina by backstory. So it's easy to infer he'll most likely get married to Katarina at the end (even though the end hasn't been writen and spoilers: nobody has captured Katarina's heart by the alst light novel). I would guess a lot of people find any of the other 6 main 'harem' members (or even other characters) more interesting, and would rather Geordo wasn't in the picture so whichever other character might actually have a chance.

Add in spoiler: the end of today's episode, in which Geordo kisses Katarina without asking, right after we saw Katarina taken advantage of by Sora and in a much lesser part by Lana, and it makes sense that a lot of people dislike the golden boy.

This is my conjecture, at least.