Let me start off saying that this is an unfortunate incident. I can't find any more details so I'll leave the particulars of what happened later on.
Here's a link to the event...
http://hyper-fest.com/
I've always said this...be careful who you DE with. It is a growing activity...more and more people are getting into it for a wider range of reasons. I've noticed this over the past 3 years in TX. I'm seeing more and more "advanced" drivers and "instructors" exhibiting very troubling behavior. I think most DE orgs have the wrong the definition of an advanced driver. An advanced driver is 1. SAFE 2. PREDICTABLE 3. AWARE. 4. COURTEOUS and 5. FAST.
Notice how fast is last. Speed differentials are meaningless within a group if drivers have the first 4 attributes. I've been on a 3.1 mile track with about 45 cars...don't have an issue if people are safe, predictable, aware, and courteous.
As an instructor...I would have had 2nd thoughts about associating myself with this event. First clue is the Daisy Dukes contest. That would tell me its a show off fest with some adrenaline added in. I can't see how that turns out good. Second is a one-off event generally has VERY poor vetting of drivers and instructors.