Are you making a broad statement or is this specific to the OP's question? Because I have personally assisted folks in getting financial help even when the PAP sign says "No Medicare people allowed".
It can happen.
Merely stating the conditions for the referenced PAP.
No need to throw down the gauntlet. Blue moons also happen . . . sometimes.
There are several options, including grants, in my links. Often in these situations grants are easier to get than PAP. The agent and client need to be receptive to all possibilities.
Copay assistance is not the same as a PAP. Copay is from the manufacturer and almosts always includes commercial insurance but not government insurance.
PAP has different rules and funding sources and may be available to someone with Medicare, Medicaid . . .