[posborne]

I think that the argument given could definitely be considered ad hominem, but as I read it definitely stuck out that a better examples of ad hominem could have been given (that has much less to do with the subject matter at hand).

For instance: "Why should we give creedence to his position on the origin of the universe? He has been divorced twice and is cheating on his current wife... Surely we can't trust what he has to say."

Here the argument is attack by attacking the person. The attack on the person has no direct translation to the dispute at hand.