I don't think there is a precedent of trades being reversed...

I don't think there is a precedent of trades being reversed after the close of the ASX?
If they do it, it is normally on the same day.

I cant see them reversing trades. Best outcome is a fine for directors and prosecution of insider traders **if** it can be proven.
Pretty clear case this given the high volume and the number of shares that were in the top5 prior to the selloff. If ASIC cant prosecute this, they may as well forget about trying to prosecute any inside trading case.