Where is the call for Rosenstein's recusal?

Referring to this article today in the New York Times, Ace of Spades writes,

We have here an allegation by the former Deputy Director of the FBI that Rosenstein participated in a cover-up of Trump's alleged obstruction of justice (consisting of the firing of Comey). In McCabe's view, Rosenstein's memo was written just to justify an illegal act.

And Rosenstein went along with it.

And McCabe has passed this memo along to Mueller -- who is, technically, Rosenstein's subordinate.

That puts Rosenstein in the same position that Sessions was in when he recused himself -- overseeing an investigation in which he himself might become a subject, and whose presence in the chain of command would be read as a "back off' signal to any subordinate digging into his role.

Sessions recused himself.

Why hasn't Rosenstein?

Where is the call for Rosenstein's recusal?