This is a thing Christians do all the time. “Well that was before Jesus.” Jesus never condemned rape or slavery (in fact, he told slaves to obey their masters). Jesus had four whole gospels to tell people to not rape and he didn’t. He also didn’t say anything negative about Solomon and his 300 concubines. In fact, he praises Solomon multiple times and says nothing about the sex slaves whatsoever.

So it doesn’t matter if it’s “post Jesus” because he laid out the rules very concisely and “don’t rape your sex slaves” was not one of them.