Doubtful of such guarantee. Future Kings might not honor such treaties and religious incentive for conversion remained. Muslims in Sivily, Italy, and Crete all disappears.to be honest if the Muslims of Iberia were conquered pre Almoravid the situation would be an inversion with the Muslims being second class citizens but without persecution. It only became a truly religious conflict with the entry of extremists from north africa .
Leon-castile would conquer the entire peninsula (without these invasions) , but the king had promised that the muslims would be treated fairly and could maintain their faith and practices (as the muslims had done with the christians). So if the conflict stayed between the iberians the situation would not escalate as it happened in otl. if the christians conquered iberia it would have a muslim percentage and if the muslims won the conflict it would have a christian percentage.