FYI: in most states the hospitals have what they may call "charity care" or "financial assistance". Your son would have to apply himself just as he has to apply for state medicaid. But the hospital (including the phsyical therapy dept at the hospital) would add up all their bills, just keeping a running tab. There would be a financial aid (or whatever they call it in your state) office in each hospital which may or may not be part of the billing dept. This office after they approve his application based on his income and assets would reduce the bill to the amount they deem he has to repay. And you could then pay that for him. Obviously as you've now gone ahead with the COBRA the situation is different. But financial aid would also apply to the deductibles and co-pays. So it's still worth asking the hospital SW about for him.
Yes, PA hospitals do it. Here's something I found on the rules for hospitals in PA re charity care:
http://www.haponline.org/public/charity_care/