An argument could be made, sure, but I don’t think it would be effective. If a person has the capacity to willingly murder their family members over an issue of eviction, then I don’t know how much capacity for reform they have. They pose an imminent and ongoing danger to anyone near them; an unacceptable level of risk in a tolerant society.
Beyond that concept, there’s very little (if any) benefit to society to reforming and releasing this man. Any work that would need to be done to ensure this man could never kill again would take a considerable amount of time. He’s already 66 - let’s say it only takes four years (somehow), then he’ll be released when he’s 70. He already has health complications which likely put his life expectancy well below average, meaning his death is probably impending in the next decade - probably sooner based on substandard penal medical care.
Trying to reform this man is like trying to keep a 21 year old dog alive - sure you can do it, and you’ll probably feel better about yourself if you do, but there’s no real benefit to the dog or society at large. He should have just been handed life without parole instead of 100 years - that seems like a sentence that could be appealed due to the silly nature of how long it is.