I doubt this has been lost on the DefCon organizers. Presumably they think that they'd lose more attendance by moving to Europe than by having people who can't safely travel to the US just not come, or attend/present via videoconference or something. And I suspect that's probably true -- very few people (in my experience) go to DefCon or similar conferences on their own dime; you go on your employer's money. And getting your employer to comp you a few hundred bucks for a flight to Vegas and a shitty hotel room (Vegas hotel rooms are notoriously cheap) is a heck of a lot easier than getting a company to cough up for a transatlantic ticket, hotel in Europe, etc. As long as the majority of the attendees are in the US, this is where the conferences are going to be.
But coming here if you're involved in cybercrime is probably, uh, not a very smart idea. That Hutchins came at all suggests to me that he didn't know that the FBI was onto his alleged previous (pre-Wannacry) activities; the alternative is that he's dumb, and he doesn't seem dumb. (Though a fair number of very smart people are also arrogant and don't give other people credit for being able to figure things out, so that's also an option, I suppose.)
There is a legitimate question as to whether there should be some sort of cyber amnesty program, though, given the number of mostly-legitimate "security researchers" who have shady backgrounds but seem to have moved on from them. I've got some mixed feelings on that. On one hand, getting blackhats and their knowledge out into the open so vulns can be remediated and the network in general made more robust is a Good Thing. But I don't know if it outweighs the message it would send, which is that you can basically play Computer Mafioso when you're young and then retire to a nice, secure, respectable position as "security researcher" without the threat of your prior activities coming back to bite you. That's not really how things work in the non-IT world; if you spend your 20s working for the Mob, and then retire to a respectable profession, that respectability is unlikely to protect you from getting a knock on your door sometime later, depending on the statue of limitations, for stuff you did earlier. Might make a judge or jury go easier on you, but it's not an ironclad defense.