Reindhart doing it with the Shambali monks probably just starts out as innocent curiosity on whether omnics have sex that ends up with Reindhart asking Mondatta some very interesting questions. Mondatta gets flustered and Reindhart finds it adorable then asks if he would like to try something, the other monks hear of this and get curious. It turns into a “Let me show you something naughty~” kind of situation very quickly.