Actually, I give him a great deal of credit here. Liberals beat the crap out of Johnson for that exchange because they know he had Hillary Clinton cornered. Her "what difference does it make" response may yet live in infamy. Nichols appears to be hedging his bets here a bit; he seems to sense that there is indeed fire under all of that smoke surrounding Benghazi. It's also clear he's still hoping there isn't.
But if this does bloom into full scandal, Nichols has done a mea culpa in the event Johnson is vindicated. But he's left enough room to turn on him again if the scandal flames out.