So, here's Trump, Jr. criticizing May for being anti-democratic and for appeasing the "global elite." Well, Don is part of the global elite. He's just part of the right-wing global elite rather than the slightly more technocratic and regulating global elite. He lands between the Koch brothers and George Soros and much closer to the Kochs for sure.
I too am for Brexit, but I want it so the Brits are out from under the less democratic possibilities afforded by the EU. I'm looking for Jeremy Corbyn to lift the poor, green the nation, and increase the general prosperity of all rather than the few. "The many, not the few" is his slogan. It's a good one. He can't really implement it in full under the EU. The EU's laws would forbid it.
Don wants the Brits to cut deals with his father not for democratic reasons but for American empire run by the elites. Those deals would pull England in particular further into the American empire and under US control. Keeping others broken up and weak is the plan. The EU is weak because it is insufficiently democratic and not integrated. The Trumps are taking full advantage of that.