I don't think the code addresses guest suites but that should not be an issue. In definitions it states this in the enhanced view. If not then IMO, the suite only w2ould not be allowed to use NM.
If a guest room or guest suite contains permanent provisions for cooking, dwelling unit requirements apply.
334.10(3) permits the use of NM in that application as long as it is concealed behind building materials that have a finish rating of at least 15 minutes.