May have realised his howler over Wallace and decided that a different headline would have that bit downgraded in the reporting, Care record number of yellows was already known about so why not go one better.
Just looked at law 3 on the World Rugby site
3.16 When a front-row player leaves the playing area, whether through injury or temporary or permanent suspension, the referee enquires at that time whether the team can continue with contested scrums. If the referee is informed that the team will not be able to contest the scrum, then the referee orders uncontested scrums. If the player returns or another front-row player comes on, then contested scrums may resume.
3.17 In a squad of 23 players or at the discretion of the match organiser, a player whose departure has caused the referee to order uncontested scrums cannot be replaced.
No exceptions for head injuries being different to other injuries
3.27 covers HIA
Thought it was a bit odd at the time and if he's enforcing it surely there would be a note on the official laws that this is the case