Right now, there's no information about Anti-GamerGate attending Airplay. However, the SPJ will still be there. Here's the quote from Allum Bokhari:

"Instead of having a verbal slapfight with the worst of GG’s opponents, you can have a civil discussion with neutral SPJ members, all of whom are attending precisely because they care about journalistic ethics.

I was quite looking forward to the slap fight. (Milo was too, naturally.) But if we’re honest, the discussion is far more important. It’s your best opportunity to convey GG’s most important concerns to an audience of experts.

Among that audience will be representatives from the most important journalistic organisations in the world. Heck, the future President of the SPJ is going to be a panelist. You couldn’t wish for a better audience."

In before Player Haters are saying "SPJ doesn't matter, they are misogynists etc. and we don't negotiate with misogynists etc.!"