Would you consider that an acceptable justification for the treatment of Dalits?

See Yvain's parable of the salmon and Vladimir's reply.

What about for a culture that permitted non-consensual sex?

If there are people who are genuinely not make uncomfortable by suddenly having sex with them, and you know this, then sure. (That such people could exist on a culture-wide level I find tremendously implausible, but LCPW and all that.) Of course what we usually mean when we talk about "cultures that permit non-consensual sex" is ones where a husband can rape his wife all he likes, or just rape culture more generally, which is obviously a different axis of variation than how much personal space people tend to have.