OT Israel was not without welfare activities mandated through the theocracy. One of the regular "taxes" was earmarked entirely for the poor. The fact that God settled the 12 tribes each in its own land did result in a degree of multiculturalism. I don't recall saying anything about open borders. Is the idea that aliens have the same legal rights as citizens the same thing as "open borders"? If so, I have not heard of that concept before. 

I don't recall writing anything about entitlements, either. In fact, the Bible does mandate care for the poor in both the OT and NT. In Matthew 25, Jesus actually says that people who do not take care of the poor will not be in His Kingdom. There is no indication that He care whether it is accomplished entirely through private charity or through government entitlements or some mix of both. Personally, I have the same attitude. 

The idea that the Jubilee teachings are "proof texting" ... I don't think it fits the definition.