In a theoretical world composed entirely of Muslims, this argument is so weak there is no way it would prevail against the simple, fundamentalist observation "Why would the Qur'an allow something that it effectively disallows? Makes no sense. You can hit your wife. The End." The only reason current devout Muslims can get away with the line of reasoning you reference in my quote above is that these current, modern progressive Muslims have the weight of the non-Muslim world, which does not permit hitting, to back them.