Yeah you're right. Sure is a shame how much he beats and abuses all the elves in his care. Oh wait he doesnt do that. Huh. He owns them because if he didn't they would be under someone elses enslavement. What a braindead response.
Not really that braindead.
The outside world sees him as a slaver, but he is not, and he can't very well correct people about it, or the wrong people might take notice and look harder at what he is doing.
Since he cannot correct people who call him bad names, then he has to just grin and bear it.
It's just the dev being creative, realistically.
If everyone agreed with what he is really doing if he corrected them, he could lose it all and possibly any chance of freeing the slaves, because he could set off alarms with the government who would start watching them.
If no one said anything bad about the MC, it would show that their plans to free the slaves would likely fail, because there would be little support from the humans.