Let me put this premise another way: To say that suffering is mans fault as god proves a point is tantamount to a parent with a family, who sensing that he/she is unappreciated, simply leaves the house to the care of their young children. To prove how valuable the parents are, the parents simply leave, thinking "That'll show them. Let them suffer."
The kids do what kids do. They tear the place down. They hurt each other. The stronger get the food and what they want, the weaker are locked in their rooms and are dependent on what the stronger siblings allow.
And this is the kids fault, not the parent(s) who walked out on them, right? Or would we hold the parents accountable for turning their backs on what they started.
So god walks out on mankind to prove his point, but the reality isn't that at all. It's a total theistic copout. Using this line of logic, the responsibility, the culpability all lies with the negligent irresponsible parents who started life, but then decided that they didn't want anything further to do with their own children.
Not a chance in hell that this is right, moral, makes any sense, or is a good argument for god.