It looks like your tacit acknowledgment that Lincoln did, in fact, use slave labor to help build the Capitol has settled her hash.
I wasn't even going to bring it up until she mentioned it.
Read it again - for the first time. I seriously doubt that Lincoln was even aware of their employment.
So are you saying that Lincoln himself personally planned, supervised and administered the building of the Capitol dome? In addition to running the country and fighting the Southern rebellion? Talk about being the champ of multi-tasking!