Purporting that to be a "claim" would be - in my opinion - an incredibly disingenuous reading of the poster's comment. Remember the HN commenting guidelines: "Assume good faith."
That is the good faith reading. The comment isn't open to interpretation. What could the meaning be if not that Preston is an uncommon example of a prisoner?
I'm responding to the claim that it's uncommon for someone in prison to have a good heart.