Why did Mark Arbib resign. Was it really for family reasons?

AUSTRALIA, Sydney -- Mark Arbib's explanation of his resignation on the surface seems clear and genuine, but when one looks at the context and the timing in which it came about, one has to wonder.

Mark Arbib was known as a "king maker" in the Australian Labor Party (ALP) and served in the Senate as Assistant-Treasurer, Small Business, and Sports Minister. As a "king maker" he was instrumental in elevating Kevin Rudd to party leader in 2006, and then in 2010, to removing him in favour of Julia Gillard.

"I have been a faction leader and I've had to make tough and unpopular decisions, but I have always loved the Labor party," he said.

In regards to context, Mr. Arbib in the December 2011 reshuffle (second reshuffle) of Prime Minister Julia Gillard, was appointed as Assistant Treasurer, Minister for Small Business and Manager of Government Business in the Senate.

Prior to the reshuffle, Mr. Arbib was Minister for Indigenous Employment and Economic Development, Minister for Sport, and Minister for Social Housing and Homelessness, since September 2010. Could the reshuffle had meant a demotion on his part having loss the Sport and Social Housing ministry?

On 22 February 2012, Rudd announced his resignation as Foreign Minister, following speculation about a possible leadership spill and later announced his candidature on the 24 February. Gillard beat Rudd by 71 votes to 31.

On 27 February 2012, after the ALP's leadership ballot, and former prime minister Kevin Rudd had failed in an unsuccessful leadership challenge to Prime Minister Julia Gillard, Arbib announced he would shortly be resigning as a minister (on 2 March) and senator (on 9 March).

Was the "king maker" instrumental in wanting to replace Gillard with the former prime minister who has since pledged his allegiance to Julia Gillard, and now sits on the backbench?