Let's say Caesars states, "we just got hacked and, as has been reported in every major newspaper, paid $10 million as ransom. We have reason to believe one or more attendees of DEF CON were part of that group."

How does making this statement this benefit Caesars in any way? Now DEF CON can demand some proof of this claim, or sue for defamation, or state that without proof, Caesars isn't acting in good faith, whatever.

I mean, attendees of DEFCON can hack Caesars even if someone else owns the projectors used for the Powerpoint presentations.

Yes, most likely. That's why it would make zero sense for Caesars to state anything publicly that would antagonize members of the community. Saying nothing (or even praising DEF CON, and claiming it was a "change in strategy") is the smarter route.