It means that there is no such thing as bad publicity.
Then there is the old show business canard: No publicity is bad publicity
The media turned politics into reality television, and now a bona fide reality television star, who understands how the game is played, has them flummoxed. He knows he is playing the "villain", but guess what? The villain gets the ratings! As long as he gets all of the attention, he harms the other candidates who are spending money to get their message out.
Think of it this way. In each week there are only 3 slots for about 5 political shows each. That is 15 chances for a political candidate, or their surrogates, to pitch themselves to the American people. Trump just sucked up 3 of the 15 slots (a full 20%) for himself. Even if he doesn't add to his poll numbers, he just blocked out three other candidates from adding to theirs. And Trump has the money (which he doesn't have to spend due to the free publicity) to outlast most of the others.
This is a huge move for Trump.
It’s corollary is, “There’s no such thing as bad publicity.”
“There is no such thing as bad publicity.”
“Any publicity is good publicity.”
branding
It makes sense in the fact that a significant part of the electorate will respond positively in the voting booth to a recognizable name when they no nothing about him or the other candidates. That’s why they call it name recognition. That’s why Jeb Bush is where he is now.