Personally, I can't figure out why Sean Hannity is so successful and I'm somewhat conservative. It's boring and he's trite, in my opinion. But obviously, millions of others don't share that opinion.
However back to the original topic, I think Scott Slade more than qualifies for "air personality". It's just not frivilous, wild, crazy, over the top. His persona is perfect for what he does---mornings on one of the top news talk stations in the country. He orchestrates the morning news show very well. Sets his people up for their stories and even for their little parting shots before he moves on. Also as noted, he is a very visible part of the community.
Of course to play devil's advocate, you could chalk his nomination up to lack of true excellence in that category.