The end of slavery was indeed the beginning of better working condition for the former slaves. You add made up words to suit your agenda.
On a similar note, I suppose he believes that "workers of the world, unite!" was a call by Marx for all the factory workers to take a day off for a casual day of picnicking and games at the park. Surely Marx couldn't have been saying "go launch a communist revolution," could he? And surely that "era of ascendency...for the working class" he was talking about couldn't have been an era of communism, could it? At least not in the foreign mental universe of #3fan's disconnected mind...
Maybe he meant exactly what he said in the quote. That the end of slavery was a good thing for the former slaves.
So it was. But that was not the view taken by Marx, who instead viewed the conflict through revolutionary communist terms. Try again.