to rot in jail for the rest of their existence

Because later on, if they were found to be actually innocent - the person rotting in jail can be released and compensated (to whatever extent false imprisonment can be compensated).

If they were executed, it’s over. The injustice can’t be remediated in any way.

If they plan to continue smoking or heavily drinking, then yes we should skip over to the next person on the list.

If they refuse to take up the lifestyle changes or follow medical advice, the organ should be used for the next person on the list.

People who’ve got transplants need to take immunosuppressants to reduce risk of rejection. Making them much more vulnerable to COVID. If the person is adamantly refusing the vaccine for bogus conspiracy theory reasons - it doesn’t give me much confidence that they would even follow through on other medical advice to prevent rejection.