If you carefully read the "Response to ASX Query Letter" there...

If you carefully read the "Response to ASX Query Letter" there is a very explicit timeline of Board Meeting (23rd) at which AS resigned during, before or after, but to which AS would have been provided with board papers. Hence, he is in possession of all the information which made up the Friday 26th announcement (prepared 24th, vetted 25th - see ASX Query reply) but not the announcement itself. At that stage he may (or may not) have known whether the announcement would be price sensitive per ASX, but as an experienced capital markets person, and being careful, would have assumed he was in possession of material, non-public information when he stepped down. Hence, there is no way he could or would have traded prior to its release on Friday 26th. Whether this announcement or anything to do with it precipitated his resignation is a different matter (and I would love to have been a fly on the wall).