He's trying to intimidate and bait you because he's a racist who has no integrity. I imagine you can unpack the rest of his reasons if you think about it. You were innocent and tried to contribute to the overall project by attempting to refine the checkuser once you made your rightful case, but the entire incident stems from the malfeasance and hubris of corrupt admins in first place. Calling someone a sock with no evidence and indef blocking them is the easiest thing to do, then have a few friends "review" the block to ensure the silence lasts. 

The exact same thing happened to me, but I was not so lucky. I'm the reason you got blocked, and I'm truly sorry for your troubles. I did nothing to warrant my blocking in the first place either, other than upset some xenophobes who are pushing their POV. A racist POV that they protect to the point where they will threaten you, like this user is doing, or even outright attack you. With users like this its not about ideals, morals or WP:principles, it's about power. Welcome to the dark world of realpolitik, be careful.  142.104.142.41