I think the situation you are describing is the formation of a monopoly among landlords in a free market. If all landlords created this stipulation then one of them would do well by catering to the desire to procreate and thus siphon a lot of renters to his dwellings. If you can still conceive of this monopoly existing, there are still some fundamental incentives to keep this situation from occurring.
I don’t know about you but, It seems to me, we think entirely too much on the could and not the would. I cam across this scenario: Two men wash up on a deserted island, one conscious the other unconscious. The one man quickly builds a bamboo fence around his companion. when the companion wakes , the one man tells him he has homesteaded all the land around him and did not interfere with him while building the fence thus respecting his property rights.
That’s the crux of it. My mind quickly goes to the fence, is he trapped? Has the companion been imprisoned? Is passively building a prison not an aggressive act? Let’s say that it is. The one man has no duty to allow the companion to stay on his land but does he have the right to block the companion from going back out to sea? Here’s why the one man has no incentive to imprison the companion in the first place. The companion would crush the one man’s head with a rock before taking his chances in the open sea. The one man does not want to fight to the death in the event the companion gets free. The one man crushes the companions head with a rock while he is still passed out. Why would this character go through all the trouble of constructing a prison in the first place just to uphold a law that no one is there to enforce.
So, if you can envision a scenario where everyone in a voluntary society is somehow forced to accept a ban on reproduction, I think you would have a situation where some fed up individuals kill these landlords, repercussions be damned.