Hi, hm, strange. I guess someone with more experience on Mac OS would have to jump into this discussion, I can't help much further from here. I was merely asking some basics and since the notification appears, the switch-over to network device mode works. So it should not be a problem on the Kindle. I don't know Mac OS enough to help you with doing firewall settings or similar, I guess something like that will break things.
A thing I did not ask yet: The addresses do not conflict with your (W-)LAN, don't they? I.e. the subnet 192.168.2.0/24 is reserved for the USB connection alone?