The difference with the Spookfish shares may be in how the...

The difference with the Spookfish shares may be in how the overseas move was managed / declared for tax purposes. You have an option to declare a CGT event when you stop being a resident for tax purposes. If you choose this option, any gains going forward are not taxable in Australia. And if you don't sell them until you move back to Australia then any gains made while not an Australian tax resident remain tax free. The country you move to also has no interest as long as you don't sell while in that country. You simply declare the CGT event again when you reenter Australia. I admit I didn't understand the ststem when I elected to declare however I am now happily watching nearmap to continue to rise knowing I have no tax hangover. Of course I would be very reluctant to sell given this ruling if nearmap shares dropped in value which may see me lose out in the end.
None of the above is taxation advice and you should seek your own advice from a professional for your own dealings, however this has been my experience and may be a way of explaining Stuart's different dealings.