Gay marriage ban passes in NC

He is correct in that He didn't speak against it.

He is incorrect in that He did not say " slavery is okay."

Not quite, as he said he didn't come to change to old rules and the old rules do say slavery is OK and he should know because .....well he is the one who is also the one so its his rules isn't it.
Now if he had said the old rules are OK apart from that bit about slaves you may have more of a point.