Is refusing to argue an Ad hominem?

Searched, but didn't see an answer, hope I'm not duplicating something...

I saw this in a forum where a person who seems to fit the standard definition of a troll brought up a point, looking for an argument. Someone was challenged to respond. That someone refused to respond because the person raising the point was a troll. He never touched the point, let alone try to refute it, just refused to go there at all because of the troll. The response was a combination of "It doesn't matter what I am, you have to argue the point..." and "refusing because I'm a troll is an Ad hominem...". I'm sure he doesn't have to argue against his will, but is refusing to argue because someone is something you don't like (ie: a troll, a conservative, a Muslim, etc.) an Ad hominem, or any other type of fallacy, and why or why not? I keep pondering this, and I keep going around in circles.

I just happened to write an article / do a podcast on this very topic last week. The details and reason are very important so I can't rule one way or another based on the information. But in general, if the "troll" made a reasonable argument worthy of refutation, and the person dismissed the argument based on the fact that the other person is a troll, then that is the fallacy fallacy (could be ad hominem as well). However, nobody is obligated to engage in debate or argumentation if they don't want. Refusing to address criticism is often a sign of poor critical thinking, but can also be due to the reasonable refusal to address really bad arguments (i.e., "the earth is flat!"), the refusal to argue with unreasonable or abusive people, or simply being too busy and not being worth one's time to address every argument (sometimes we have to pick and choose the arguments we address due to limited time - the hope is we don't ignore the ones that challenge us).

An Ad Hominem attack is name calling. Someone who is keeping his peace (that is, not saying anything) is someone who is keeping his peace.

BTW, if the person refusing to answer is a U.S. citizen and is pressured to answer, he can say this: "I'm invoking my rights under the 5th, 9th, and 10th Amendments to the U.S. Constitution." End of discussion.