Hi. I am sorry that you don't have the land anymore, that's a really awful situation and I am sad to hear it. And it's a shame that this new owner of the land wants to hold it for himself and not let others hunt, especially a kid. I am not sure how the altercation about the backdrop factors with this guy, but obviously it put him off. Unfortunately however, he now owns the land and it's his to do with as he pleases. I don't see why he couldn't offer your son an area he must stay in, but could hunt. Eventuallly when I buy up some land, factoring in those that have previously hunted it would be a consideration, at least giving time for these folks to find new opportunities elsewhere. But ultimately it really is up to this man to do as he pleases now, and I don't think anything you can say would really change it. I wish I had a better impression, but from what you say, this man is pretty adamant that he's the boss now. I'd start looking for other places for your son to hunt.
He could do some legwork and ask other farmers in and around the area. He might begin the conversation when he knocks on the door saying that he's from the area but recently lost access to where he hunts, as the property was sold. If I owned huntable land, and a nice kid came up and asked for permission to hunt, was from the area.. polite,etc. I'd likely let him.
I wish the best of luck to you guys.
And then the moon, like to a silver bow new bent in Heaven