Look at the British National Party, they were piratically nothing until the BBC decided to massively increase their coverage. Was the BBC's coverage fair and impartial? Probably, but just giving them the attention causes people to look into their platform and realize blaming everyone else is a pretty comforting thing to do rather than take responsibility.
The deep question is who should be the gatekeepers, and I guess John Etchemendy is saying it shouldn't be universities. Perhaps he's right in a way, the board shouldn't be making those decisions. I do think the faculty and students do have a right and duty to though as giving platforms for hate speech empowers it.