As I said up above ...
Not that I agree with what has been done here - but in regards to what you say - someone who was smart and slick about it (in taking over the house) would always have two or three people around as witnesses, be armed himself ... and ... if any altercation happened, call the police immediately, who would then arrive, look at the legal paperwork, and say, “It’s a civil matter and you’ll have to fight it out in court.”
If the previous homeowner tried to “do anything physical” about it, without going to court - then he would be subject to being arrested.
Where the hell do you live, New York?
Show the police your deed. Do not do anything physical, do not try to eject the trespassers just refuse to leave and file the criminal complaint.
In this case it is shoot, shovel, and shut up.
Fine, arrest me and let a jury of my peers judge me on why I dropped the guy (and his buddies) where he (they) stood on MY property. I'm fine with that and just did the state a favor.