Bearklr hit the nail on the head. I would take his advice and speak to your buddy, explain your displeasure and try to convince him to take a doe or a decent buck. But, you have to put yourself in his shoes and imagine the excitement he had when seeing the deer and shooting it. Only 3 years of hunting so don't fault him too much. Just reiterate your management plans and shrug it off.

If all else fails, put him in an area where he cannot do much damage. Friends are friends and good ones are hard to come by!