A project like this is extremely impressive. The guy deserves a lot of credit (and maybe some investment?). That's hacking in the truest sense.
The parent's checklist misses a bunch of things. For instance "1) Hookup a computer to the CAN-Bus network of the car". That alone is not trivial. It is trivial if you want to read the car's odometer, but good luck doing more than that. For instance, people are still trying to make sense of the reported battery cell voltages in the Nissan Leaf. All interesting features are not documented and require serious reverse-engineering. "Hooking up to the CAN-Bus" can easily become a task for a whole month, full-time. Not to mention that the most useful features for the self-driving part are probably not accessible by the CAN-Bus - people are still trying to unlock the doors of the aforementioned Nissan Leaf. Steering, acceleration and braking are unlikely to be on the CAN-Bus "2) Attach a bunch of peripherals" is also hand wavy, and same goes for the rest of the post.
It would be like dismissing SpaceX accomplishments by saying: "1) Build rocket frame. 2) build engine 3) Program flight software 4) Fill up the tanks with fuel 5) Push a big red button". The devil is in the details.
With that out of the way: if the events happened as described, this guy should be convicted of reckless "driving". Taking a prototype that had only started working a few hours prior to an actual test run in a freeway with other cars is insane. What about some simpler, more useful and less dangerous goal? Such as a lane-departure warning add-on for cars which lack that capability?
The article title is the worst part though. It's not "clever dude created a self-driving car prototype by himself". It is "Dude is taking on Tesla by himself". Which is bullshit.
EDIT: Fix typo.