I don't see the problem
Again, he's saying that some people "infer a Truth." I can read that either that they infer that there is a Truth, or that they infer what (they believe) that Truth to be. Either way, it's an inferrence. And if, as the rest of the quote says, that inferrence is at odds with what they would like to believe, isn't that evidence of not being a slave to their preconceptions?
I can't be a Democrat because I like to spend the money I make.
I can't be a Republican because I like to spend the money I make on drugs and whores.