It’s the DNR that makes this one tricky. His lawyer should have made the argument that keeping him alive against his will instead of letting him die constitutes cruel and unusual punishment.
first, as this is an American prison you will probably want to be using the money on your accounts to buy food that to eat instead of depending on the often inedible, non-nutritious stuff that is available from the prison kitchen.
second, it's quite a well known scandal regarding how systems are set up to rip off inmates for phone services https://www.prisonlegalnews.org/news/2015/jul/31/inside-shad... so if you are a prisoner with money that is nice that you can actually call people when you want as long as you want.
third, depending on where you are at the commissary probably has other things you want, and if you have enough of those things you can trade that for other things inside that you might want.
(of course you do not legally access the money, it is on an account that you can use, you can also - although the process can be convoluted - release money to visitors and those visitors could give it to other people who are related or confederates of other people inside allowing you to buy other things that way [which is of course going to be against the rules])
I could go on, but I find the question somewhat weird - I'm guessing you must be from a country with no knowledge of American pop-culture or anything because this is quite a bit past even 10000 territory https://www.xkcd.com/1053/
On what grounds? He is serving a life sentence. He is in the custody of the correctional facility. They have every duty to keep him alive and healthy, up to the point of him expiring naturally.
Ridiculous logic games like this are a pretty good reason why excessive legalese is mocked in mainstream culture - because it is totally disconnected from reality and enthralled with their own existence.
The correctional facility's role is to incarcerate him, restrict his freedoms. I don't think it's unreasonable to think that there's a line that needs to be drawn there, from my perspective as an emergency medical provider.
There's still some role of autonomy here. Even as a prisoner he is allowed to determine what he may read, may do (within restriction), when he goes to the bathroom. Saying "No, you have no right to determine what medical treatment you do or do not receive", to me, undermines a civilized society, even for the incarcerated.
"Sorry you were diagnosed with amazingly painful metastasizing bone cancer. If you should go into cardiac arrest, be advised, though, we will not let you pass - we are going to work to keep you alive. This may result in brain damage to you. But so be it. It may result in long, expensive and painful procedures for the rest of your life. But so be it".
Note that this is different to, say, hunger strikes and force feeding, but instead about medical conditions.
Should they keep him on life support for fifty plus years, in theory, just so he can "serve out his life sentence" to the satisfaction of the state, for example?
From a medical provider's perspective, and similarly, someone with custody over another, ignoring and actively violating their medical treatment wishes (in my state, the POLST form - Physician's Orders for Life Sustaining Treatments, which has replaced and expanded upon DNRs) is just as much assault and battery as anything else, and may also be considered negligent and malpractice.
