"The loving side of King Von"
I think Imu DOES love most species, hence why the Sunlight Tree Eve provides light to the Fish-Men. I think Imu is a segregationist, rather than really racist. We haven't really see any outright "racism" from Imu, so much as "yeah, this tribe and ours are incompatible due to ideology".
The Celestial Dragons racism STEMS from this segregation, but I don't think Imu themselves hates Fish-Men, or anything like that.
I think, based on the discrimination Imu dealt with for being... really freaking different, Imu believes the only way the world can be functional is through segregation/classism. Luffy wants to unite the world and make everyone equal, Imu believes it's impossible for other tribes to actually coexist, and that the coexistence is what leads to culture clashes/war in the first place.
Pretty much what Green Bull says here.
Imu seeks to stop Joy Boy's war/rebellion/liberation, and instead seeks peace through Dominion.
This also really explains Vegapunk's words regarding Imu: I think Vegapunk came to the same conclusions I did. Imu DOES very evil shit, but, in their mind, it's worth preventing another Void Century War. The racism/slavery is worth the stability.
Obviously, Oda disagrees with this, hence the story.