I classify your example as ad hominem. Some other formulations similar to your example are:
An opinion about war held by one who has not served in the military or fought in combat is not legitimate.
Intellectual insight from one who is not college-educated is invalid.
An understanding of the rigors of pregnancy on the part of a man is erroneous (male medical doctors who practice obstetrics and gynecology would disagree).
This is a particular flavor of ad hominem that I have encountered often, and I sympathize with the urge to distinguish it from other fallacies. It certainly seems like a counterpart to the appeal to authority, a variation in which one does not vouch for an argument on the basis of alleged expertise, accomplishment or privilege but instead dismisses an argument on the basis of an alleged lack thereof. This illustrates where the confusion lies, and also identifies an important fact. Appeal to authority is an affirmation, while ad hominem is a negation. I view the two fallacies as counterparts, though I never encounter them characterized as such. They each shift emphasis and scrutiny away from an argument and toward an arguer. Your example, however, is properly termed ad hominem because it fallaciously negates an argument, and does not fallaciously affirm one.
Put more simply, a reversal of an appeal to authority would be an impugning of authority, which would be to say that one's position is invalid because one lacks the knowledge or experience to hold an informed opinion or put forth a cogent argument, which is to attack the arguer and evade the argument, which is ad hominem. Q.E.D.
I think it is more to the point to identify that ad hominem and appeal to authority are the same device applied in two different but complementary ways. Each approach says, essentially, "when evaluating this idea or opinion, consider the source (and only the source)."
One can appeal to authority (a privileged position or frame of reference) in many ways: an argument about patriotism must be true if it comes from a Republican; an argument about morality must be true if it comes from a Christian; an argument about economics must be true if it comes from a successful capitalist; an argument about law must be true if it comes from an attorney; an argument about climate change must be true if it comes from a scientist. If each of these is reversed, I find ad hominem attacks: an argument about patriotism must be false if it comes from a Democrat; an argument about morality must be false if it comes from an Atheist; an argument about economics must be false if it comes from a welfare recipient; an argument about law must be false if it comes from a criminal; an argument about climate change must be false if it comes from a layman. Therefore, while it is technically correct to term your example ad hominem I assert that your identification of your example as a reversal of or opposite to the appeal to authority is essentially correct, and that perhaps new organization and nomenclature, which would identify these fallacies as two sides of the same philosophical coin, is in order.