You said you listen to a few rappers? I'm not sure, but I think as long as you keep listening to rap, it will keep showing you rap songs on your Release Radar.
Again, I'm not sure, but I can imagine that the dislike button won't necessarily make it stop showing entire genres, but more specific songs and artists.
Personally, I think this is good because a lot of people listen to genres they just don't like some artists of.
I'm sorry I can't help you any further, maybe Spotify Staff can. Have a good evening.