I don't see anything in the article to suggest that he personally planned to do a rebuild himself, or that he had done so previously, only that having it rebuilt, again, was a possibility to be considered. The rules concerning working on your own aircraft are sufficiently complicated to not be worth going into here, but it boils down to, for most factory built aircraft, that the really simple maintenance, change oil for example, can be done by the owner, anythings serious has to be done by a licensed mechanic. However, it is not unusual for an owner to do work on their aircraft while being supervised by a licensed mechanic, and in fact, if you are so inclined, it is considered by many to be advantageous, both in terms of money saved and in terms of ensuring you know what was done and that it was, indeed, done right. Plus you get to know your aircraft far better than the non-mechanic pilot.

I find nothing unusual about a person flying at his age. I know and have flown with numerous pilots who are in that age range. Some are better than others, but the same can be said of pilots at any age. Some of the finest pilots I know are in their 60s and 70s. I wouldn't say they were typical of their age in almost any respect. For that matter, one could argue that it was his considerable experience that allowed him to control the aircraft after the mechanical control failure where a less experienced younger pilot might well have ended up dead in an out of control crash.

Non-commercial pilots in the U.S. must pass an FAA physical exam performed by a designated FAA Aviation Medical Examiner (AME) every three years for pilots under age 40 and every two years for those age 40 and older.