Yes, a standing ovation for this. I'd love to live long too. But not at the detriment of other people's lives.
I know it will be nearly impossible to create such a world without sacrifices but your character should have at least asked for permission to take a life.
I am sure there are lots of people out there who would be willing to sacrifice their lives for such a noble cause.
I can't even imagine being trapped in a room for years, plotting my escape and revenge.
Ah, I feel bad for the detective or lawyer (captor) who locked him up, he will meet his end and will never be one of the immortals.
Dark? Yes. Loved it? Absolutely.