OK, fair enough. I'm all for private agreements.
But if I had a media company, a website perhaps, I'd not join the coalition of "all" broadcast media.
This is a large nation; many others would refuse to join such a coalition to boycott "negative" ads.
I, and many others, would gladly accept ads that tell the truth about someone like 0bamao.
And the truth might just be percieved as negative toward him !
If such a boycott movement ever gained traction, public support for it would be so overwhelming that only the smallest and most obscure outlets would ignore it.