Most Asians in north america were slaves long after the blacks were freed, look up the tale of the railway chinese workers. So if anyone is justified in racial violence, it would be the reverse, but NO ONE is justified to use violence because some asshoe twenty generations back was a prick. That mitigating measure in mind, it is entirely possible a random pair of Asian people in that timeframe owned slaves, and that they were not good owners. After all, statisically speaking, more blacks in the south owned slaves than whites, per-capita, so slavery stats can be fascinating to look into as to how it all happened, from the comfort of centuries between us. Anti-black racism is also very common in the modern era in many Asian cultures, they are notoriously xenophobic after all, they don't even like other Asian cultures, let alone whites who share their ideology, and it just gets worse as it goes down the dissimilarity chain until you hit the literal concentration camps China is currently using today on some of their population.

TLDR; it's probably true, the core fact situation at least. The context around it is likely questionable.