I was wondering the same.
I checked and found that his website is still up, though it doesn’t look like any new content since last year.
I wonder if he simply burned out. I once had a popular and large website that I had online between 1999 and 2012. It was 4x4 and history oriented, focusing on the Great Basin (Nevada, eastern California). Juggling a job, a disabled wife and creative content can be a heavy load. Finally I had enough and put my priorities where they belonged. If he burned out, I can emphasize with him.