This is just a form of the “well...they did it too argument”, the real argument should be no one will be paying for any slavery that happened 150 years ago and the Republican party is focused on ending slavery in the world today in places like Africa, and Democratic cities like Houston, New York, San Francisco and Los Angeles just like we did back then.
and in this case it worked like a charm. You can't reason with leftists, you have to beat them at their own game. And McConnell played it to perfection.