I'm pretty sure ad hominem doesn't mean what you think it means.
And I'm quite certain that his listing of funders could be easily verified. So unless you have information to the contrary, I'd characterize that list as "fact based" vs "misleading".
An ad hominem (Latin: "to the man"), also known as argumentum ad hominem, is an attempt to link the validity of a premise to a characteristic or belief of the person advocating the premise.
The accuracy of the list doesn't stop it from being ad hominem.
The misleading part is suggesting that $612k of donations is decisive in a budget of over $24M.
You need to get it straight. If you say something nasty about Cato and I attack YOU personally, that's ad hominem. If you say something about Cato and I attack Cato or some of its supporters and explain why, that's not ad hominem, and no matter how many times you post a wikipedia page, that doesn't change.
It depends on the explanation, specifically whether the attack goes to the substance of their position or, as in this case, "they're bad companies", which makes it ad hominem.
> And do you just run around posting "ad hominem" 100 times a day and downvoting opinions you disagree with?
It's easy enough to see that I haven't. I also haven't killed any puppies this week.
Any other questions?
You understood that you were making an ad hominem argument that was misleading?
> but the fact that these are the type of entities that supported this enterprise is telling enough.
I note that you didn't bother to tell us who supported the other side....
Wouldn't that also be "telling enough"?
From http://en.wikipedia.org/wiki/Cato_Institute "According to its annual report, the Cato Institute had fiscal year 2008 income of $24 million."
In short, the "list of funders" is both ad hominem AND misleading.