It sounds like defcon was mad at EE for going over budget - which honestly is fair even though they didn’t handle it well. And thought (wrongly) that Dmitry was a salty subcontractor of theirs. Their actions make some sense in that context. Not great, but eh.
But Dmitry has totally owned them in messaging - by forcing them to physically eject him (making a scene), and getting out ahead of the story. It’s great drama. He’s positioned defcon to look like an evil corporate buffoon hating on a hacker who was just donating his time.
At this point, defcon should take the L and apologise, and let him have a session talking about the code. That would be a very satisfying end to the drama for attendees. (Even if it does encourage more drama in future years.)
Either way, I agree - I’m sure attendance will go up next year too. People love this stuff.