I was getting all geared up to argue with you, I looked up the OSI definition, and ... you're right. I wasn't aware the OSI had a definition, that'll be very useful!
Super cool project! Will definitely see if I can't get something set up at home with this.
I actually recently did my own framework, in connection with my bachelor thesis on IoT and (a little bit) mobile networks, that focused a bit on home automation, but HomeKit is obviously far more polished than what I have[0]. The general field of IoT/M2M is very interesting.
The only gripe I have with it is that it is not open-source, which would definitely be awesome (HomeKit, that is). That said, not being open-source is not going to stop me from not using it.