They can have whatever needs to be done outside of the US. There are many countries that would accommodate Rush and a donor.
Actually Rush said very definitely in one of his shows years ago after that heart scare in Hawaii...that he is self insured. Last I heard his contract paid him $57 million a year...the price of a life savings procedure is no object for him... he just refuses to deal with the bureaucracy of insurance etc.
As far as the extreme age issue - in Nevada, with Humana Medicare it is 1 and younger and 70 and older. I was told that if a person is on the transplant waiting list he is removed on his 70th birthday. I am not currently in need or one and don’t anticipate one...so I looked no further and just accepted that what I was told as accurate.