Tons of conflict of interest, this at a minimum:
The investigation was ultimately supervised by then-U.S. Attorney Rod Rosenstein, an Obama appointee who now serves as President Trump’s deputy attorney general, and then-Assistant FBI Director Andrew McCabe, now the deputy FBI director under Trump, Justice Department documents show.
Both men now play a key role in the current investigation into possible, but still unproven, collusion between Russia and Donald Trump’s campaign during the 2016 election cycle. McCabe is under congressional and Justice Department inspector general investigation in connection with money his wife’s Virginia state Senate campaign accepted in 2015 from now-Virginia Gov. Terry McAuliffe at a time when McAuliffe was reportedly under investigation by the FBI. The probe is not focused on McAuliffe’s conduct but rather on whether McCabe’s attendance violated the Hatch Act or other FBI conflict rules.
The conflicts you mention are real, but can be compartmentalized within DOJ (at least that’s valid legal reasoning).
Sessions appears to be correct on the law. However, I believe DOJ is derelict in it’s prosecutorial discretion.
Conflicts in which a SP are expected by tradition and demanded by the expired law are conflicts associated with the POTUS.