Def Con has 30,000 attendees. And maybe 99% of them aren't assholes.

But in such a large group, there's always going to be some people who'll decide to muck around with their hotel room's locks or something like that.

you say that like a person informed enough to know what a white hat is lol. Let’s be real here, even the ethical hacker bunch can look VERY wonky and rowdy to an outsider, especially if you are as far removed as the hospitality industry. The only time they had to deal with hackers in the recent past was decidedly painful for them

If they hadn't hosted Def Con for the last 20 years I'd agree, but this community certainly isn't new to them.

being ambivalent towards a group, filling up your hotel, but otherwise alien to you, may be a little less polarizing than just having been forced to shell out $100M to a similar sounding demographic.

Primarily, it's about public image. It would look idiotic to host this group, regardless of intention. And it's about insurance -- logical or not, their insurer probably insisted they quit inviting DEF CON and associating, in any capacity, with self-identified hackers.