Even though his iPhone has a built-in spellchecker, and a web browser that can be used to look up anything, John doesn't have the patience or attention span to use the correct spelling of common words or proper names in his "official campaign tweets" or letters to campaign donors.
Everyone makes mistakes, especially in the fast-paced world of social media, but John’s errors demonstrate such egregious and consistent carelessness, that I contend that he really isn’t someone who can effectively write code.
I don’t think writing code, at least when you are talking application development on top of some framework, is incredibly difficult – it’s a skill learnable by most people who can solve SAT/ACT type word problems and have enough self-discipline to work through the process long enough to gain some familiarity and competency with the tools and process. Unfortunately, I don’t believe John fits into this subset of people.