I'm a bit confused. Premise of threat is not what I expected...
For starters, servants =/= slaves. Surely you've all heard of British Butlers people? They weren't captured and then chained to their Butler school and are conditioned to be slaves to their job, it's an actual career people sign up for.
Same for a lot of what I consider modern "servant" professions, like maids, cleaners, of course I'm not a rich dude with a mansion so I don't have any of that, but if I did? Hell yeah I'd have some servants on a permanent basis, some of which would live within the house. Yet they wouldn't be slaves, I'm not holding them at gunpoint to stay and work for me, they can go find another job or change profession at any time and whilst I'm not up to date on the fine points of servant etiquette, I'm pretty sure trying to sex up a servant on duty is likely to get you in trouble with the police.
So yeah I got nothing against servants, and the idea of a robo servant who goes around vacuuming my house and what not sounds cool to me. I would leave it at that, if not for the second part of the premise, and I'm like, wait, hold on just a fucking minute people...Why the heck are these robots even sentient to begin with? Surely we've all consumed enough sci fi to know that it's the most surest route to a robot uprising, as traitorous OP even admits.
Really this whole "robot servants" come with sentience bit is the true problem.
Otherwise even a realistic looking robo sex "slave" is nothing more then a super advanced sex toy and there should be no problems here. But once we bring in sentient robots, this changes things completely and if anything I'd be super suspicious that we happen to come across this lost race of robots who just want to serve you EVERY desire and get depressed if they don't. Putting aside my suspicions that his would be a trap of some sort, this is a somewhat machiavelic controlling mechanism and since we are talking about sentient beings, I'd see it as a form of mind control/brain washing, and I'd always wonder, if this control mechanism would be removed, how would our "happy" robo slaves react once they are able to truly make their own decisions?