Of course, we should give up on our perceived possessions. Anything we think we own is anatta as well.
But slavery in ancient times had a lot more nuance than what it devolved into in US, even the treatment of white vs black slaves and subsequent racism was a big factor. We could even argue that, there are a lot of contractual obligations in nowadays that are like slavery with a few more steps, and thus Human Resources departments could be considered to be slave traders.
But going back in history, you would be hard pressed to find any kind of ruler who didn’t have slaves. It was literally the norm.
Slaves owned slaves. Slaves ruled districts, cities, empires. People voluntarily chose to become slaves in many cases, because the rights, privileges and livelihood the status offered. Being slaves to important figures was a prestigious status. This is clearly a different world than the one we’re accustomed to.
Just because I own (which, I actually don’t, but for the sake of argument) a laptop, doesn’t mean I’m abusing it, treating it badly, hurting it, inflicting suffering on it. Or, technically I own my cats depending on how you understand the animal passports and pet related laws. I don’t hurt, abuse, inflict suffering on my cats. Am I an evil person?
Yet, someone trading animals for a living might be in a different predicament, actually participating in the trade.
I think bhante raised an important and interesting topic that challenges our modern notions considerably. Of course, giving up householder life, we should relinquish our (notions) of possessions entirely. But perhaps, several kings and holy people from the past, despite owning slaves and still attaining attainments, teaches us a humble lesson in compassion and redemption, which I think it the most important part of this inquiry.