I enjoyed reading and reminiscing about the bygone glory days of big deer herds in PA.
A few observations about the neighbors 3/4 mile away shooting all of the deer;
1. Being very concerned about this situation sounds a lot like me, but I try to avoid obsessing about things beyond my control. I'd try to file this story and forget about it. Life's too short to clog my mind with how to program the latest electronics, and such like.
2. It may not be true; I have observed that if an individual in the neighborhood gets excited about local events, the local wags and pranksters just invent bigger stories for the benefit of watching the individual get even more worked up. The local factory where these losers work has a policy "if you don't hear a rumor by 10:00 in the morning, by all means start one".
3. My longterm experience observing deer movement on multiple cameras scattered across several square miles of area tells me that few deer in Pennsylvania types of habitat move or range a 3/4 mile if they have everything they need locally. My one friend has a thousand acres with excellent habitat and a high deer density. Right beside him is a thousand acres of open woods public land with low deer density. The interesting thing here that many hunters have discovered after fruitless days of hunting is that very few deer cross that property line in one direction or the other.
So, I'd suggest that you focus on the things that you can change. Better habitat on your land. More food, more cover are the simple keys to holding deer. In deer language acreage means nothing, ten acres of thicket holds more deer than several hundred acres of open woods.
Also, my experience is that having slob hunters on a neighboring property is often a short-term condition, these guys, whether they be landowners or, more commonly, lessees, are usually as transient as the wind, running after the latest rumored hot hunting spots and wearing out their welcome within a few years everywhere they go. Hunters who stick around for the longterm are generally the ethical ones who have an invested interest in the future health of the deer herd and care about more than just slaughtering animals and drinking beer.
So hopefully that story isn't true but I'm predicting that (hopefully) it won't affect your success this fall. Good luck.