If a Paper is Submitted to Nature, Does it Still Make a Sound?

Suppose you (and perhaps a competing team) had an incredibly exciting discovery that you wrote up and submitted to Nature. Now suppose that you (and the competing team) simultaneously posted your (competing) papers to the ArXiv preprint server (which essentially all astronomers and physicists visit daily). But, suppose you then wrote in the comments "Submitted to Nature. Under press embargo". In other words, you wrote the equivalent of "Well, we've submitted this to Nature, but they won't might not accept it or publish it if the news gets into the press, so can all of you reading this just not actually, you know, tell anyone? Oh, but can you make sure that you give us credit for the discovery, instead of the competing team? Thx!" So, instead of blogging about the Incredibly Exciting Discovery (which I'd loooove to talk about), I'm writing about what a ridiculous fiction the authors are ...