But on the other hand, there were active abolitionists going back to the early 1700s. The idea that human beings were equal and that the ownership of a sentient person is wrong is considered intuitive to most civilized people today. It's a bit revisionist to extend that expectation back to 1912, but his particular brand of ethnocentrism is just this side of vile. But in fairness I must mention that he disliked his own Human species in general as well once describung us all as "a bastard mess of stewing Mongrel flesh without intellect, repellent to the eye, nose and imagination..." So I'd add misanthrope to the list of charges.
But his contribution to the Sci-Fi cannon, and radio theater is without question. Rats In The Walls for example was published in 1924, and not rendered into a radio play until the late 1980s by Atlanta Radio Theatre Company and aired on WGST-AM.
Rats In The Walls (Part 1 and 2)