Prematurely maybe, because there was no allegation of crime involved vs. the Trump campaign.
The appointment of SC was on grounds that existed in public (Comey's March 20 testimony in Congress), and had no relationship to Comey's being fired. Indeed, Rosenstein would have to recuse himself from a case involving the Firing of Comey, because Rosenstein is the one who composed the written justification for firing Comey. That was a big deal among the press and commentariat for a week or so, at various times.
That is what is most bothersome.
RR writes justification for firing Comey.
Comey is fired.
Mueller meets with Trump (fake interview?)
Next day is appointed by RR to investigate Trump Campaign with no crime identified.
No push back on that....coincidence? seems very orchestrated by who?