Based on my experience with ASX (working for an ASX100), what seems likely is that the Company submitted a release at 7:45 (as per the tweet); this was rejected by ASX (as speculated in AFR) and the company told such; and the company then sought a trading halt (likely on the request/suggestion of ASX. This is why the TH request is on company letterhead).
GSW Price at posting:
$2.92 Sentiment: Hold Disclosure: Held