Although it is quite true that the people most often quoted by conservatives were liberal for their time, by modern standards they would generally be considered reactionary.
The most famous example of this may well be Thomas Jefferson himself, who kept slaves (and depending on who you ask, may have even fathered a few of his slaves' children). But there are others. By modern standards, even Abraham Lincoln, so famous for freeing the slaves, was actually quite racist.
No, I'm not trying to justify racism or slavery. What I'm trying to point out is that when you try to examine a historical person's political views, it's important to view them in not just a context appropriate to that time, but a modern context as well. the reason: statements like the title of this node have a rather nasty tendency to be found inconsistent.