You're right with regard to emergency treatment; so in the case of the withdrawal patient that holds. But hospitals are not required to accept any insurance, in

You're right with regard to emergency treatment; so in the case of the withdrawal patient that holds. But hospitals are not required to accept any insurance, including medicare/aide (they are termed "non-participating"). So I don't think the premise holds in the knee-replacement scenario. So, to be generous, maybe there's a case that if a hospital gets a bulk of its revenue from the ER, it's a better business case to accept Medicare. But I don't believe that's the case for most hospitals, so it still leads me to question the premise that medicare is a net negative (or else we'd see a lot more 'non-participating' hospitals).