I agree Sessions is not recused from going after his own team, maybe just doesn’t want to be put in that position, so let someone else lead the effort?
I can't recall an AG ever personally issuing an indictment, conveing a GJ, etc. The question of recusal is more one of being informed than of "driving the bus." AG have been known to spike or encourage specific investigations or prosecutions, but are not the hands on people.
Sessions is out of the loop if the case is vs. the Trump campaign, or vs. Hillary, or vs. the Clinton Foundation. If the case is vs. anybody else, he is or can be "in the loop," to whatever extent he wants to be.
There is good reason to suspect Rosenstein would spike internal FBI/DOJ investigations if he could somehow keep Sessions out of the loop. He has friends involved. I think Sessions doesn't have that baggage, and also has cut Rosenstein out of all but the three classes of defendant noted before: Trump campaign, Hillary personally' and Clinton Foundation.