Doesn't this hide the underlying reason that the Egyptians simply wanted the conquerers done away with?
Re. the hippos, they were animals sacred to Seth, and the Hyksos kings were enthusiastic Seth-worshipers. It's nothing to do with being evil or bad, it was just that they had their capital in the eastern Nile Delta, which was always the place for Seth-worship. The later great Rameside pharaos, like Ramses II etc., were all enthusiastic Sethists as well, and the family hailed from the easten delta.
In the context of the Hyksos-Thebes conflict, it was a way of the Theban rulers to claim that the conflict was also religious, a re-run of the mythological coflict between Horus, son of Osiris, murdered by Seth. Horus was the chosen diety of the rulers of Thebes, Seth of the Hyksos.
As for the Egyptians wanting the Hyksos out, the Theban rulers certainly did. Otoh, there were all kinds of deals made, allowing the Thebans to graze their sheep on Hyksos territory in the Delta, which tells us that things weren't overly hostile until the king of Thebes, Ahmose, decided he wanted it all.
And when the Thebans did roll north, they were faced with the situation of Egyptian towns resisting them, wanting to go on being ruled by the Hyksos. Well, they couldn't have that, so they burned these places and impaled the locals on stakes as "traitors". Again it tells us that maybe the Hyksos weren't that bad or impopular rulers of Egyptians.