Not exactly the sort of use I normally envision for Teensy, but then at least it's good they're "white hat" folks publishing this and working to improve the security.
Maybe not all "white hat". Just three days ago, one of my neighbors reported getting her car hacked
(from Nextdoor.com Lori L, 8/3/2015 ) I had my car broken into when I was in LA and the thieves are very sophisticated, they have some device that allows them to override the computer and not break windows or doors.
Samy uses Teensy in a lot of his projects and they're really cool. Rolljammers have been around for a couple years, though this may be the first diy. I think its good that a person like Samy is publicising this to make people aware of the vulnerabilities.
Eager to watch his defcon talk.