Honestly in this case I don't even think it was about his age. Reaaally imagine what this dad went through before his daughter got the kidney. To see your kid wither away forced to go through dialysis( which I've heard is pretty fucking awful) day after day, then the relief when they finally got better. If I was in his shoes I can imagine I'd want to do the same for someone else going through something so horrible, and let their family get that same relief mine got to enjoy.