Sounds like a person in the grip of a big idea, wrapped up in their own thinking. That can be a pain to deal with but it tends to be self-correcting. If someone stops communicating with people effectively, others will withdraw, and that isolation eventually causes pain. Eventually the person who's off in their head will start to notice their needs are not being met, and as they search for a way to return to earth to get what they need, they'll have to do the work themselves to understand others and present their new ideas in a coherent and sensible way. Pulling away from a friend who's talking nonsense can sometimes be the most loving thing to do.