Ah, another example of how A"ad hominem" is misused;) Please see my other reply listing three different sites using three different definitions of "ad hominem". None of those definitions support your example. Rather, saying it is so because "he's a distinguised prof" is an appeal to authority, which is not _always_ a fallacy.
People who can't understand an argument are reduced to "who ya gonna believe?" Then we begin to hear about sources of funding, motivation, nationality, religion etc.
I'm glad to see that you place all these arguments down near the name-calling level.
I enjoy your essays, Bill Drissel Grand Prairie, TX