Ann: Appointment of Managing Director and CEO, page-4

It is not a sign on bonus it is for loss of entitlements that hewill forfeit on resigning from his current employment. Whilst I don't agree with it, it appears to be standard practice now days and if you want the best(if he is) you have to be better than what else he may be offered.
At least this time the board put some sort of half decent guideline around it.

Transition Benefits: On a one-off basis, David will receive the following transition benefits as partial
compensation for vested and unvested STI, LTI and other entitlements that he
will forfeit on resigning from his current employment:
• AUD 1,270,000 cash payment on commencement date; and
• AUD 3,700,000 of rights to acquire ordinary shares calculated by
reference to the 90-day VWAP over the period that ends five ASX
trading days before the commencement date, with 50% vesting on the
first anniversary of the commencement date and the remaining 50%
vesting on the second anniversary of the commencement date. These
rights will not be subject to performance hurdles but are otherwise
issued on terms similar to performance rights.
Other than to meet any tax obligations, no shares held by David can be sold until
David holds sufficient shares to meet the company’s minimum shareholding
requirement.
The transition benefits equate to approximately 80% of the total potential
entitlements that David will forfeit, the majority of which are not at risk and
subject to time-based vesting only.