"If it just was an average of the SP, they could have changed it up to a minute before publishing as nobody knew about it anyway or they could have waited a couple of days or weeks."

Contrary to what people believe, decisions of this nature are not done in a few hours. It takes a bit of time, positions are committed to and then executed while the market goes ahead and does what it does. You can't really run a business and make decisions as quickly as some might think.