As you said it yourself Dante didn't give Vergil that much time to explain himself so maybe he didn't really meant to rule them but to lead them?
Even if he really meant to rule them still it doesn't necessarily means that he wasn't fighting for their freedom! The problem with Vergil and Dante could have been that their definition of freedom were different! Dante thinks that freedom means letting humans do what ever they want to do, let them decide their own future! And I agree with that.
But we don't know what was Vergil's definition of freedom! He said that he wants to rule them because they are like a child, that they are weak! For all we know by ruling them Vergil could have just meant to being able to protect them from demons he has to be in place of power!
There is no way to tell what Vergil would have done to humans, or whether he would have given the freedom to them or not.