Are you mis-attributing the use of 'no platforming; to Peter Tatchell? I don't believe he actually said that, and it was rather a media invention. Generally it's been quite clear that this was not an official policy, so it can't really count as no-platforming.

(It may be unrelated, but I'd point out that refusing to share a stage with one of the world's foremost gay rights activists is a preposterous decision in this case, and I'm glad it was roundly ridiculed. Even if it's not 'no-platforming' as such, it's still a bad position to take, and stinks of the general idea that debate is too much work.)