Muslims will always do that --- find some obscure event that may or may not have happened 1000 or 4000 years ago to justify what they just did.
When Mohammed is criticized for ordering massacres and such, his defenders will say, "In those days, Christian rulers did the same thing." That may be true, but no one holds his contemporaries such as Justinian and Theodora of the Byzantine Empire up as models for humanity for all time. That's the difference. Christians did things then that are not acceptable today -- most Muslims, mentally and morally, are still stuck in the early middle ages.