The fact that someone like Spencer would be attracted to Trump speaks volumes about both men. Trump has never spoken publicly about Spencer, but he has not publicly condemned him nor has he disassociated himself from who he is and what he represents.
Spencer is also openly un-democratic and speaks both favorably and longingly about dictators and dictatorships. It's no surprise he admires famous fascists in recent history, including Nazi Carl Schmitt, who for a while was a close confidant of both Adolf Hitler and Hermann Göring.
This paragraph portion in the article caught by eye: "Liberalism accepts that disagreement is part of the political process, and that people who disagree profoundly can live together. But eventually, Schmitt argued, the parliamentary debate does end, and someone gets his way while someone else does not. The state’s job is to provide not the coffeehouse for the debate, but the threat of a beating to compel the loser to accept the result."
That paragraph describes totalitarians and dictators perfectly. It describes thugs like Vladimir Putin, Rodrigo Duterte of the Philippines, Recep Tayyip Erdogan of Turkey, and Abdel-Fattah al-Sisi of Egypt, all of whom Trump has showered with adoring praise. Trump has also made positive comments about the likes of Kim Jong Un, the North Korea dictator, Bashar al-Assad, the Syrian dictator, as well as the late Muammar Gaddafi and Saddam Hussein, both murderous and brutal sociopaths.
"The threat of a beating" is also the tone Trump conveys about his many domestic opponents. He refuses to recognize that democracy is an ongoing dialog of opposing viewpoints. He often speaks violently and brutally about anyone who opposes him. He has openly encouraged and condoned violence directed against anyone who protests at one of his rallies.
It's perfectly clear: Trump is both President of the United States and also stridently un-American. That is nothing short of horrifying.