Sounds to me like he may be trying to develop a decent deer herd. Leaving the big boys alone for 2 or 3 years while getting the herd to stay on, or close, to the property will aid in the genetic development of the herd. Getting rid of the scrubs and making the buck-doe ratio much closer will, in a few years time, improve the over all genetic development of the herd.
Ask him if that is what he is trying to accomplish. If that is it, then by all means go along with it. It will be good for the deer as well as good for your freezer. Bucks over 4 years old are pretty much only fit for burger and sausage. So taking out a 3 or 4 year old thats sporting a spindly little fork horn will be great for the freezer and great for the overall genetic structure of the herd.