There 'concern' was without merit. It was a flimsy excuse to start any investigation.
why would the FBI be so chaotically concerned if Rosenstein agreed with the Pres? was the concern really that Stokes, Page, Fusion, etal would be outed in turn, as, in fact, they were? If anything, it lends credence to (was it Clapper who said it?) Comey considering the dossier his ‘bible’ - his excuse to ‘investigate’ Trump, develop an ‘insurance policy’ and then set the Great American Red Herring distraction in motion by leaking to the press.