Here's why. He has proven himself to be ANTI-AMERICAN by siding with "the enemy" against the citizens of his own country. He believed Putin NOT the intelligence agents. He agrees with Kim about the intellect of Joe Biden. He insulted/attacked a GOLD STAR FAMILY. Even after Senator John McCain's death the sb prez attacked and insulted him! The draft-dodger old codger said he didn't like people who were captured. Had no respect for them. His jealousy/envy of McCain is well-known. He can't stand anyone who is brave and served his country well. It makes the cad look real bad and he cannot stand that so he tries to make others be as small as he is. Laughable clown. A great punch line.
He throws American Citizens under foreign buses all the time. What makes you think on a battlefield he wouldn't have shot Americans to suck up to the foreigners? He does that figuratively DAILY.
What makes you think he could be trusted with a loaded gun to shoot "the enemy" when without a gun he sleeps with them and lets them have their way with him and shoots fellow American citizens down with his insulting views?
He cannot be trusted. He cannot be trusted. He cannot be trusted.