The Pope has used this white chair, instead of the traditional throne seat.
Up until now, he has only used the traditional throne seat once. In his other meetings, with religious leaders and diplomats, Pope Francis has used a simple white chair, which is usually reserved for weekly general audiences.
Another point is that the chair is not elevated on a platform, rather it's kept at the same level and height as other seats. In fact, during his meeting with religious leaders, he used the same type of chair used by the guests.