People use policy to refer to a simple stance on things all the time, they don't have to codify it and put it in a company wide handbook.
Tony certainly wasn't asking Mark to wrestle last week, don't be silly, but he obviously wanted to do more as evidenced by the tribute show they were forced to sandwich in between Dynamite and Rampage.
So what changed that they're allowed to honor Jay with what I'm assuming will be a 10 bell salute, a video package and someone or a few people giving an address, because something obviously changed, one of those things possibly being an already less strict stance on Mark being waived -- because SRS also just tweeted this
"I'm told the new bosses at WBD gave AEW the permission to book Mark Briscoe on Dynamite." almost like they didn't have permission previously