While the isolated statement itself is technically not incorrect - think of freed slaves who survive by growing cotton on their own after the end of slavery for example - it is obviously used with the evil intention of implying that slavery was in a way beneficial to the slaves, which is a particularly sickening form of historical revisionism, especially when considering that the people who made the statement are probably descendants of slave owners who still financially benefit from slavery because of their family assets.
This is exactly their process, if their constituents swallow this as acceptable then feed them the next, slightly worse thing. Slavery was horrible and we haven’t recovered from it as a nation.