I say, and with God's help: In the countries where they are accustomed to the optional Dhuhr prayer, it is permitted and preferable in their lands; because it is a prayer and an act of devotion to God Almighty. In the countries where they are not accustomed to performing it, it is not permitted to pray it; as it may lead to confusion for them as long as the conditions for the validity of Friday prayer are met. And God knows best.