A flawed SC appointment does not make the recusal flawed. If (emphasis on the conditional) indeed there WAS a criminal investigation / prosecution involving the Trump campaign, Sessions is properly recused from it.
I would go a step further, in that if there was a counterintelligence investigation into the Trump campaign, Sessions should recuse from that as well. This because there is a possibility that the investigation would turn up a crime, and if Sessions was in charge, he'd "pull a Holder" and bury the crime.
Where I don't go, and what I blame on the DS/DOJ -- which is successfully blaming Sessions for following the regulations so as to avoid the appearance of conflict -- is sequestering Sessions from FBI / DOJ malfeasance and a few other cases that contain no allegation of wrong against the Trump campaign.
FWIW, Sessions is also properly recused from cases against Hillary - recused during confirmation hearing on account of he has prejudged to lock her up.
BTW, my blacklist isn't personal. I bear no animus. Just my contribution to keeping the peace, short of vanishing.
There was a different piece that said that Sessions didn’t have to recuse himself. That he got snookered by careerists at the DOJ. If you can’t find it, I’ll see if I can. I think it was McCarthy, but not sure.