Anyone they hire that goes against absolutes is a good thing. Unless that lack of absolutes is absolute. Oh wait...
I'm glad a d20 expert is back into the mix. Not only to avoid the excesses of 4e design, but just as importantly of 3e's. Being intimately familiar with the mistakes of the past two generations of D&D is a terrific thing in a hire for 5e.
Good for Wizards landing him. The two sets of books that I purchased went towards something.
But I find it so ironic that I was just mentioning how I didn't like their idea of fixing a balance issue in basic D&D with a feat fix in standard, or a substandard PHB option with a strictly superior option in AU. And his blog mentions the arms race of immunity vs immunity piercing feats escalation.
As well as the disavowal of absolutes. Like the absolute ability to completely negate any chance of an AoO when a swashbuckler runs around attacking 3 things a round. They could have done so much better, like say such attacks are at disadvantage, or he has resistance against such attacks. Literally pertinent in so many ways to the latest AU article they just published yesterday.
Hopefully he brings another voice for rational game design to avoid such absolutes or endless arms races or power glut that 3e and 4e were cursed with. But I see a lot of the issues of 3e and Pathfinder could easily have been fixed through errata yet weren't. Many people believe 3.5 is not much of an improvement over 3e for many classes. And Pathfinder is well known for having many classes like Summoner that are pants-on-head _________ed.