Ann: Intention to demerge Coles - Briefing Presentation, page-18

"Just WES will maintain a 20% stake for tech developments and control. Equally a blocking stake for any TO."

On the contrary, a facilitation stake in a takeover situation.
As in, "If anyone wants to takeover Coles, come and talk to us, and at the right price, you can have our 20% block, which will already get you well on your way to gaining control in just one single transaction, without having to first scour the market for blocks of stock to kick off your acquisition."

In other words, they are making it easier - not harder - for Coles to be acquired.