That certainly appears as if you ...
or words to that effect, what followed was dead wrong. Absolutely incorrect. The fact is, DiLorenzo talks of nothing but Lincoln. All I did was acknowledge that simple fact. It's not ad hominem. You're wrong to think it is. Incorrect.
Your so-called "fact" was gratuitously asserted to begin with and, given due scrutiny, fails to hold up as a fact. A quick search on Amazon.com reveals that Thomas DiLorenzo is the author of some 10 or so books, one of which is his Lincoln biography. The remainder cover a variety of wholly unrelated subjects including public healthcare policy, political lobbying, the economics of charities, and government food and drink regulation among others. Thus your conclusion that he writes only on Lincoln is not only wholly unsubstantiated but, seeing as the majority of his published work is on entirely different subject matters, also wholly off base.