I think science is a forum, and that forum is telling him "You have been consistently wrong, your predictions have been worthless, and we prefer to give the lim

I think science is a forum, and that forum is telling him "You have been consistently wrong, your predictions have been worthless, and we prefer to give the limited speaker slots to people with a better track record?" He's not being silenced; he can say whatever he wants, but the conference isn't obligated to lend him creditability by making him a speaker.