What would you do? Asked whether someone should have a child because it will give them free college.

The cost of a child over 18 years is going to cost him far more than what he is going to save over 4 years. Even if you broke it down to the first 4 years, it's a losing deal financially. That's without getting into any of the other issues.

That would be after I had asked him how many times his parents dropped him on his head as a child.

That is a bizarre and selfish reason to have a child CSM Michael J. Uhlig. To be honest it would take me a moment to get my blood pressure down before I answered.
It would be sad if there was a woman/girl who concurred with this young man's plan.
Raising a child takes an incredible amount of time, effort and patience. Raiding a child as a single dad is a very challenging project - I did it not by choice after my first wife decided she wanted to be with somebody else.
For this young man to raise a child by himself for the sole purpose to "get free/reduced tuition rates in college and that he wanted to go to college for 10 years at the reduced &/or free rate" he must be very callous so as not to care what happens to the child and incredibly foolish to think the amount he saved on college would offset the costs he would experience by being responsible for raising a child.

What would I do?...keep calm and try not to throat punch the poor misguided soul. Just as LTC Stephen F. and Sgt Aaron Kennedy, MS already mentioned, I would explain the cost of raising a child versus the cost of actually paying for your own education. I have 6 kids myself, so I can draw upon a wealth of experiences in how much actually goes into raising a child that is beyond just dollars. I know you set this person straight CSM Michael J. Uhlig.