"And if it isn't a big deal, why did you truncate the quote to make him appear less uneducated?"
Perhaps for the same reason you give no credence to his first sentence that clearly indicates Trump knew he wasn't around during the Civil War? As I said, it's not exactly show stopping news in the U.S. 
"History is certainly open to interpretation, but Lincoln had a strong moral objection to slavery ...."Your attempt to paint him as uncaring on the issue is disingenous."
I made no such attempt. As I stated he "was not a proponent of slavery". But his words leave no room for interpretation. His main objective was preservation of the union. When the  Emancipation Proclamation was issued the north had trouble filling their ranks. Enlistees were fighting for the preservation of the union, no to free the slaves. Hence the uptick in the draft and formation of black units comprised of free men and former slaves who escaped to the north.