How did this happen? I think Dick Morris, who is familiar with the New York City talk radio scene, may be right in his pre-debate August 6 column Trump Can Win:
The establishment is waiting for Trump to make a mistake. But even as he tip-toes over the line of political correctness, his detractors need to understand that he – unlike they – is a media pro. Where they may occasionally appear on camera, Trump does it every week. He constantly threads his way between critics and says what he thinks. Doing so in a political context is no big deal for him.