coturn does not appear to be very Instant Messaging specific, hence it should not be in CATEGORY=net-im. net-misc/stuntman, an implementation of the STUN protocol, is in CATEGORY=net-misc, where I think coturn also belongs.
I don't think we should put it in net-misc. A) It is related to realtime video/audio which is "instant" and "some kind of messaging" B) misc shouldn't be cluttered with stuff that belongs to an existing category If you have another reason to use an s/tun server, then please tell me. I am not aware of any.
Then net-misc/stuntman should also be in net-im.