Wow, that's upsetting. That will annihilate the deer herd within a couple of years. He should have a conversation about his concerns.
They can’t possibly have good access going thru the timber or even along the edge without blowing everything out. Especially with a prevailing west wind. I don’t believe you’re far from me as that seems to be the prevailing wind here. Unless I’m looking at it wrong.
A lot to unpack there in a small amount of space. I am just assuming your brothers 4o gets used for hunting? Most of the time you can't choose your neighbors and what they do on their property, but you can choose how you deal with them. If they are neighborly I'd start with talking to them and getting an understanding on what their goal is with selling hunts. If all they are doing is selling hunts in the tower blind, its probably not over concerning. If they litter the woods with bow stands that gets a little more challenging but as mentioned they still need to hunt it and the wind plays a big factor. If they are neighborly and tell you what the plan is, that would give you the most information to tell you how to react for the best hunting on your brothers land. Ideally if you have a 2 foot topo map for those properties that can tell you what the hunting looks like on those properties and the ones around them. If you haven't already the county GIS map may be able to show you 2 foot topo. Regardless of what their plan is there are plenty of things you can do to improve deer hunting opportunity on your brothers 40. If you know their plan you can really pin down what work you could do to improve hunting for that 40.
It sounds like they are mostly brown & down gun hunters. He's not trying to control anything they're doing next door...just frustrated with how the season is going.