I say, and with God's success: Zakat al-Fitr is not obligatory on the disbeliever; because there is no way to impose it in a state of disbelief; as it carries the meaning of worship and cannot be fulfilled without intention, and the disbeliever is not among the people of worship. Refer to: Al-Badai 2: 70, and Al-Wiqayah p. 229, and God knows best.