Well cockroaches can survive ridiculously high levels of radiations and diseases while us humans can get totally destroyed by any disease if not treated. Plus it's the FOOD chain, not the social chain. The food chain is based on what eats what. Humans are at the top because they can eat any animal. Vampires would drink/eat humans so they'd go on top of the humans. And maybe add the damn Sabercats next to the vampires too >:( cause they eat both humans AND vampires
As a ruler, no way I'd support that. Citizens pay enough taxes, why the hell would they be obligated to pay, this time with blood (not during a war) and to keep around creatures that are potentially dangerous?
If the vampire really means no harm, he would toughen up, come to a priest/priestess/healer/alchemist (anything that stands for a doctor), explain his situation and the person helping him would try to find a way to help the vampire, even if it wasn't something possible. The healer or whatever could then proceed to try and convince someone to donate, after explaining the situation. But it would all have to be consensual between all parties, and definitely not through the government's enforcement for the "greater good".