Sessions is a complete traitor.
The only way the Russian collusion accusations can harm Trump is if there is a very partisan, anti-Trump investigation.
Sessions did not have to recuse himself. If he, or anyone even moderately reasonable handles the investigation the "no collusion" conclusion comes out early and it is over, except for punishing the guilty.
The only way it can hurt Trump is if someone partisan who is adept at generating process crimes runs the investigation. Enter Mueller and his band of RAT lawyers.
Sessions knew this going in and allowed it to happen...
* * * * * * * * * * * * * * * *
Now for the good news. The guilty parties prolonged the investigation, hoping to escape justice. But, they committed even more crimes while doing it.
Sessions was wimpy.