From what I’ve seen, most people are assuming “big guy” is Sleepy Joe, but I’ve always thought it could be several different people. Sleepy Joe and BO are my top 2 picks. But maybe Brennan, BHC, or several others.
To me, one small argument against it being Joe is that it sounds odd to my ears to have Hunter calling his dad “the big guy”. Not out of the question, but I don’t know anyone who calls their dad that, especially in the context where he did it. That seems much more like the way you might refer to your dad’s boss or some other important person who is not your father. JMO.
You left out Gorge Sore-a$$