Well, they COULD decide to euthanize humans because they dont want humans to do to the rest of the galgaxy what they do to themselves.
If I were human... wait I am... I'd still not consider myself racist for trying to stay alive, even if it involves killing a few sparkly-glowing space aliens with big brains.
Apart from the the fact that the the key word in "racist" is "race" and not "other non-carbon based bio-engineered life form that tries to make me exinct".