As far as I know (from an interview with Geoffrey Robertson, Assange's lawyer, but also known as a respected senior lawyer and public figure in both the UK and Australia) this is incorrect. It is possible to be elected when overseas, however there seems to be a grey area as to what would happen to his seat if he was unable to return to the country to occupy it in parliament.
It's not really a grey area. There have been politicians who have failed to be present enough days in their electorates in the past and suffered the wrath of the electoral commission.
This is quite simply untrue. There is no requirement to live in an electorate to represent that electorate in Parliament, and in fact in the past it was very common for country electorates to be represented by city politicians. Antony Green has a great post debunking this myth:
Could you be thinking of housing allowance scandals? This is where elected politicians claim rent from the government for rent for houses they're not really living in.
As far as I know (from an interview with Geoffrey Robertson, Assange's lawyer, but also known as a respected senior lawyer and public figure in both the UK and Australia) this is incorrect. It is possible to be elected when overseas, however there seems to be a grey area as to what would happen to his seat if he was unable to return to the country to occupy it in parliament.