You mean well in ignoring their argument, but please don't let people get away with whitewashing history! It was not a "different kind of slavery." See my comment. The chattel slavery incurred by the Israelites on foreign peoples was significant. Pointing out that standards of slavery toward other (male, noncriminal) Israelites were different than toward foreigners is the same rhetoric as pointing out that from 1600-1800, Britain may have engaged in chattel slavery across the African continent, but at least they only threw their fellow British citizens in debtors' prisons.

Good point. That wasn't my intention. I meant to steelman his argument, to show that even under those conditions, his argument makes absolute no sense.