Timing is everything. Their time will come.
Jarrett and FR groupthink have been howling for Sessions’ and RR’s heads seemingly forever. The one guy who knows more about those two than all of the outside critics combined is the same guy who can fire them at will. And yet he doesn’t.
Occam’s Razor. The simplest explanation is that Trump, unlike those not privy to what he knows, is satisfied with the job that they are doing. No convoluted explanations needed for why he doesn’t act.