So, what's your point? Do they need to actually suffer in the same way in order for justice to be achieved? Because that's the implication he is essetnially driving at. The important thing is those abolitionist recognized a moral wrong for what it was and strove to counter it. To insist in such a way that they can never understand not only invalidates their efforts but only tries to set the stage for some kind of further remediation. But maybe that's their aim, to make sure it is never ultimately remedied and preserve the well of victimhood. How else can you read that.