I'm down with the idea of developers getting together and forming a common standard for Markdown implementations if they want to do so, but Atwood & Company have consciously and deliberately thumbed their nose at Gruber through this whole process. They could have just called it "Plain Text Markup" and explained in the first paragraph that yes, it's Markdown with all the ambiguities taken out. Hell, they could have called it "PTM: The Standardized Markdown Specification." They could have even called it "Pandoc-Flavored Markdown," which AFAICT is (mostly) what it is. But "Standard Markdown" came across as we are taking control of Markdown over your objections and the way they developed and announced it greatly amplifies that reading. I'm not convinced "Common Markdown" is much of an improvement, and the "Well, we're pretty sure this will make John happy even though we didn't actually wait for his response" definitely doesn't help.
I would guess the answer to be "Release it anyway", because Gruber's blessing is not something that was considered a requirement.