How can the author be a "former professor"? Academic misconduct?
Lots of professors leave academia to pursue other careers. It frequently happens when they're denied tenure, which has nothing to do with misconduct (there are a lot of junior faculty competing for a small number of tenure slots). In a field like CS, professors can get much higher salaries working outside of academia, so many are tempted to leave.
Professor is a title for life. You don't lose the title just because you leave academia.