You implied, that it was implied, by the comment you responded to. The KKK is a terrorist organization. There’s no implication that a terrorist organization gets to advertise just because they paid, in the comment you responded to.

This anti-Biden website, being anti-Biden, is not in the same category as the KKK.

So the answer to your question is no. The KKK doesn’t get to buy ad space on that radio station.