I'm not so sure that his snide remarks about slavery and usury are correct, either.
But imprecise allusions are the hallmark of the Father of Lies and his mortal allies.
As I understand it, popes were among the first to speak against slavery -- I think against its spread to the New World; I never heard that any came out in support of it. In fact, I would venture to guess that, in many times and places, demanding an end to slavery would be something like demanding an end to employment today (surely you saw the buttons a few years back: "At least they can't fire me. Slaves have to be sold!") -- given the conditions, where would the slaves go?
Usury is still condemned AFAIK -- it used to mean charging any interest at all; it has been redefined to mean exorbitant interest, as economic theory evolved.