Great point!
I have a feeling that some slaves might view homosexual acts as a lesser sin which is not for them to call, but something to consider nevertheless.
It's something I need to work through. I've only gottten to the point that homosexual acts were condemned in many places in the bible and always by the church, whereas slavery, although condoned or not specifically condemned, was not intended to brutalize or demean another human being; it was a form of servitude which has had many variations through the centuries; many immigrants came to America as indentured servants as well as the poor souls who came bound in chains on slave ships and condemned to an unpleasant life. I do think that a few slaves in the old south became devoted to their masters and would have rejected "freedom".
We still have "slavery" by consent today that would not be frowned upon, you work for me for a certain amount of time, and I'll give you free room and board; whatever the two parties agree upon. The only difference is the coercive element. But one could argue sometimes economic conditions in diverse times and places have coerced people to become unpaid servants, work as a nanny or taking care of an elderly person for free room and board, for example (usually there is some money exchanged). So long as it was mutually consentual, I don't think there are any laws on the books in America to prohibit the practice per se.
Maybe some greater mind has wrestled with the concepts. This is not a good time to bring this up because I've got a lot to do and should be getting to it.