So, basically, there are still wrongs in this world so it's legitimate to celebrate other wrongs, such as slavery. Using this boneheaded logic, no one can criticize any wrong until all wrongs in this world, in this country, are eradicated. Furthermore, you're equating the conditions of someone in slavery with the undocumented.
Alternatively, you're taking a position that to criticize one wrong means to in the same breath list and acknowledge all others. Silence on those subjects means to at least accept them as inevitable, or perhaps necessary.
I have a feeling the undocumented who paints your house, goes home to a wife and kids, and whose family isn't seized, separated and sold to another painting company 1,000 miles away would disagree. His wife who isn't raped with impunity would disagree, the kids who aren't whipped bloody would recognize a fundamental difference between being a slave and arguably exploited labor. And the key to the undocumented is they made a choice - slaves had no choice, no opportunity to improve their lot, their kids doomed to the same fate as the parents, for all time.