Would discount that rumor for several reasons:
1. Garrett's not calling the plays, Moore is, and Moore's pretty much an unknown, still, at this point, the future, even with Garrett is pretty muddled.
2. He's on a team that has talent and is at least in the running for a title, albeit not that high a probability.
3. Garrett is at least a good possibility to get fired, no matter what Jerry says. Jerry's famous for saying one thing then doing another, the "Zeke who?" comment was interpreted by many to mean he'd not pay Zeke, but he did, didn't he?
4. How many commercials would Dak get as a member of say, the Dolphins? The off the field opportunities for Dak as the quarterback for the Dallas Cowboys, one of it not the top job in sports, are huge, even if they aren't winning a lot.
5. Holley's a minor player in the sports broadcasting arena, very likely he's spreading rumors to pump up his presence.
6. Nobody even knows for sure if an offer to Dak is said and done, or in negotiations, or Dak has rejected it forthwith, haven't heard Jerry or Stephen said anything definitive.
I could come up with a half dozen rumors as to why Dak is not signing, doesn't mean it's true.
We'll know for sure eventually...