As long as it's able to get at the Macbook that's what counts. One could use that same/similar excuses for most Windows exploits. That never stopped the Applebots from attacking Windows at will anyways.
What does that prove?
That the macbook is not as secure as Steve Jobs and the Applbots claim? In fact, Win 7 has consistently proved to be more secure in tests than Snow Leopard.
It doesn't "get at the MacBook" at all. It just tells the router to ignore MAC addresses in a range that MacBooks use.
The same "exploit" could be used in reverse, telling the router to only let MacBooks connect and block everything else.
Proves nothing other than the router is easy to hack, not the machines connecting to it.