Bad crypto key handling, again. The big problem here is the lack of a secure way to introduce all the devices to each other. You can't securely do this over wireless alone. But you should at least have a system which doesn't allow adding or deleting devices from the network while armed.
If you want to incorporate physical security, you need the devices to be physically linked to be paired. I suppose you could use a custom made USB device to simply transfer the keys from the devices to the hub.
That would work. It can be a problem if you have to re-key and the device is in a hard to reach location, such as a building-mounted camera.
The problem with many of these devices is that they're all too willing to talk to things that don't have their key. That makes them vulnerable to attacks.
