The existence of borders that are enforced restricts the freedom of movement of individuals. The existence of the state is irrelevant. If you assume a state then borders need only be enforced against aggression.
The issue of open or closed misses the real problem, state welfare payments. You can be in favor of open borders and ending tax payment to everyone in "need".
I don't disagree with any of what you've said. My article shouldn't be taken to present an argument in favor of one position over the other. However, in what I've read thus far regarding this line of debate, there have been a number of people that equate a preference for a state with closed borders to a preference for a state, and they're not the same thing. This is especially true when the conversation presupposes the existence of the state in the first place, which any conversation about state borders necessarily does.