Rent/mortgage, retirement completely ignored.
Plus he has the shittiest $82 health insurance plan he could find, and he doesn't calculate the costs of what will happen if he gets sick.
On average people after 65 spend $2,920 per year on medical out of pocket expenses (Source: http://www.newretirement.com/Planning101/Rising_Medical_Cost...)
Then his food comes from his garden, which means he has to work on that, and he conveniently didn't calculate the opportunity costs, tools, irrigation, chemicals, seeds, etc.
What about transportation costs, electric/gas, phone, internet, household supplies, upgrade of your old computer, clothing, shoes.
Then if you want to have a car (and it sucks to live pretty much everywhere in the US without a car), what about car insurance, maintenance, new car every X years?
Yeah, it's fucking easy to live on $7K per year when you own a house with a garden, don't pay property taxes, use 1995 computer, and have no safety net in case of a serious sickness.