I think your scope of college students is too narrow. You do not have to do well in high school to get into some kind of low tier college. Low tier colleges will take anyone with a pulse who can get a loan.
According to The Directory of American Philosophers, 1980 edition [0], he taught at Franklin and Marshall College at that time. Probably with a little more digging, you could come up with his academic CV. The school is a small, expensive, private liberal arts college that's (currently) well-ranked in the US News rankings[1].
So, what's the likelihood that the incoming freshmen at Franklin and Marshall (a) had trouble with "cats/cat's/cats'" and (b) hadn't written any papers in high school?