If he was only selling to the Australian market before, he could still just sell to the Australian market on a foreign site. The postage rates would still be local postage rates (but probably in euros). I've seen Chinese sellers who will only ship to the US and Australia and not China. I think that's where the international blocks would come into it.

I have encountered Aussie sellers on eBay US and the postage was what I would pay for a Aussie sellers on the AU site, but if I changed my location to the US, then the postage jumps to international rates. It's just listed in US $$.