It sounds like that “powerful” senator just passed on info specifically because he couldn’t verify it. All indications are this was a dossier that no one could verify the contents of and therefore no one would publish it. You say “both Trump and President Obama had been briefed on its contents by senior intelligence…

Uh... no. It would be if Trump had been arrested or indicted based on this report. He wasn’t. So it’s actually completely unequivalent.