There is an awful lot of handwringing and complaining about Sessions recusing himself with regard to the presidential campaign. While I understand that frustration, I would surmise that one of the big reasons he did recuse himself when he did is that the deep state was going after him for his supposed contacts with the Russians. My guess is that Sessions knows that he himself was the subject of 24/7 spying . . . Even during the campaign.
As I recall the chronology, the deep state went after Sessions. After a day or two he recused himself. Supposedly PDJT was angered by that, but then we got the Saturday Morning Tweet. That weekend I think there was a big powwow at Mar a Lago (including Sessions) and there was the announcement that congress should investigate the “wiretapping.” My guess is that this is strategy to get the gravity and the breadth of the corruption out in the open slowly through a political process before finding the best judicial avenue. The reality is that anyone PDJT considered for AG would have gotten the unmasking treatment. Being a victim of a crime, or at a minimum a witness to a crime would make recusal the only honorable action.
At some point there will be enough of the breadth and depth of the spying out there to go forward with grand juries, etc., but there is a little ways yet to go.
By recusing himself, he can TESTIFY in hearings and in court.