He has a 6 month notice period, so he is still around to see out...

He has a 6 month notice period, so he is still around to see out the completion of the refinancing, which according to recent announcements, is progressing well with multiple parties engaged in due diligence (as I suspected was the case in my earlier comments). This would explain why it has been such a drawn out process - multiple parties due to no one wanting to take on too much of the debt/risk (again, not surprising). 6 months is also plenty of time to hand over to the new CFO.

A new CFO coming in soon after a new CEO has been appointed is very common. I wouldn't be surprised if the replacement is someone who Mat Cooper has worked with previously (a known quantity).

Being CFO of a publicly listed company would be a demanding and stressful gig, particular one of a company that has been through what AMA has in the past 3 years. There are myriad possible reasons why he could be moving on. I wouldn't be reading too much into this. The announcement wasn't labelled as market-sensitive for good reason.

Just my 2 cents.