A professor emeritus not decisions to take up courses is nothing like quitting. You don’t need to make up excuses for deciding to not take courses, it’s pretty much the default.
Imagine that you retire from your job but tell your boss: “I know I’m retired, but Inwouldnt mind coming b once in a while just to say hey and catch up with people.” Would you then call it quitting or getting fired if suddenly you decided “actually I’ll not be stopping by next year”
More like, “I know I’m retired, but I wouldn't mind coming in once in a while just to say "hey" and catch up with people.”
Would you then call it quitting or getting fired if suddenly you decided “actually I’ll not be stopping by next year, BECAUSE MY SON IS CONVICTED OF THE LARGEST FRAUD IN HISTORY, AND I WAS THERE HELPING HIM THE ENTIRE TIME, BUT IT IS JUST COINCIDENTAL THAT I WON'T BE STOPPING BY ANYMORE.”
Boss: Thinking "Phew, glad I didn't have to tell her not to show her face around here every again" but saying to her face, "Oh, ok...it's up to you, but I totally understand that the only reason that you are not coming by is because it is your own decision that has nothing to do with YOUR SON IS CONVICTED OF THE LARGEST FRAUD IN HISTORY, AND YOU WAS THERE HELPING HIM THE ENTIRE TIME, BUT IT IS JUST COINCIDENTAL THAT YOU WON'T BE STOPPING BY ANYMORE.”