Old saying, "Racism is not born, it's taught."
And that's no truer than in the case of Sprout Cloverleaf, you could tell as a colt he was still open to being Sunny's potential friend, despite being misguided, but his mother's instance on the fear that she was passed down with, and now passing on to her son. Only deference is that Phyllis unlike most, actually see the errors of their ways and changes to stop her child from going all out. Thankfully, it really in the end, just a misguided antagonist, I never saw Sprout as a villain, an antagonist, yes, villain, no.