The trading window is open now and closes April 6th. As per your post (which I double checked) the only two people with more than 100k shares who are considering selling, are CEO Mike Westrup with 4.6 million and Shane Booth with 2.2 million.
Then the announcement says "Shriro" (whatever that means. Chairman? Managing Director? Remuneration Committee? Some other internal committee?) decided only 25% is allowed to be sold.
Mike Westrup was a recent on-market buyer, so presumably he does not wish to sell now such a short time later. That leaves Shane Booth. So, if that logic is correct then this Trading Window Update announcement is because one person wishes to sell. Perhaps in the interest of clarity and straight-forwardness it would have been better to just state Shane Booth wishes to sell some shares and tell us the reason.
The announcement was written by the two people who it affects, who write in such a way to make it non obvious who will be selling.
I wonder what Chairman John Ingram thinks about this. Perhaps he should be the person taking charge in such a matter. It is all a little bit strange.
SHM Price at posting:
80.0¢ Sentiment: Buy Disclosure: Held
(20min delay)