No, you aren’t missing anything. Banning is for all “automatic” play situations (i.e. where you haven’t picked that specific thing). That includes album play, artist shuffle, radio, etc. There is no “just ban this for radio”, and I’m not sure there should be.
As I mentioned above, Roon automatically removes a lot of tracks like this from Radio. I don’t think it would auto-exclude those “Dialogue” cases, however. Maybe that is something for us to expand (@mike–this is for you. Also consider “applause”, which is not in the current list)