Yeh that is a shame for Mason. I am a bit concerned Lynagh may end up in a similar situation, he puts his body on the line in defence quite a bit.
A couple of interesting narratives which are kind of related to this. After the Super W on the weekend, the 7s girls who played were all very vocal about how much more physical the 15s game was and how many extra collisions they were in. A couple sounded a bit skeptical about doing it long term.
In comes back to a few conversations I had years ago, where some of the QRU and QRL well-being officers actually had an informal 'task force' to discuss the future of the 15 and 13-man games in regards to concussion and how to better integrate 7s and 9s as genuine pathways. There was research being done around the reduction in collisions and head knocks etc.
But interestingly, since then, both comps have seemed to drop off those versions of the game. World Rugby is looking to cut the 7s tour back and the NRL basically have no officially involvement with any 9s competitions.