A LOT of stupid here. I won't go into that of the trespassers, because that's a given.
Hunters trespassing and two people approach them?
Hunters = armed. And deer hunters aren't likely to be armed with sharp sticks and rocks. They're going to have guns.
If they're trespassing like described, they obviously don't give a $#!t about property rights and therefore are likely to lean on the belligerent side. Belligerence and guns are a poor mix to go stepping into.
Put dogs in the mix, especially dogs belonging to belligerent idiots, and you've got another wild card in the mix.
And I'm sorry...you can't go deliberately blocking people from leaving on the one hand and then tell them to get off your property on the other hand.
As soon as the nephew called, he should have had the nephew back off, called the sheriff, and gone to ensure his nephew got out OK...and taken pictures/video along the way.
And stayed on the phone with law enforcement the entire time.
Potentially losing your life, or even your health, over the actions of unpredictable, armed idiots isn't doing yourself or your family any good.
Now, on the other hand, eff these people and eff them in court. And I hope all three get shafted in the legal system.