If there is a clear conflict of interest - I agree. But does the mere fact that Sessions was nominated by Trump constitute such a conflict? In reality yes. Legally? I don’t think so. But I have to concede that even if that is true it could be grounds for an appeal - with all of its attendant uncertainty.
So - ok I agree with you.
I do not believe that Sessions has a conflict of interest just because he was nominated by Trump. In this particular case, I believe Sessions has a conflict of interest because the investigation is going to involve potentially illegal surveillance by the Obama administration -- and Sessions himself may have had his phone or e-mail communications intercepted.
I believe Sessions may have a conflict of interest because he may be a VICTIM and a potential WITNESS in the case, not because Trump happened to nominate him.
In other words, the actual reason for Sessions' recusal may not be what everyone assumes it is.