NO!! Mueller should RECUSE HIMSELF. Just as Jeff Sessions was forced to recuse himself for attending an Obama cocktail party that also included the Russian ambassador, Mueller should recuse himself for being asked to investigate his friend. This should be the one and only line from ALL Republicans henceforth.
I believe that on June 8, the Justice Department issued a statement showing that Mr. Sessions' recusel was required under 28 CFR 45.2, primarily because he was closely affiliated with the Trump campaign which was under investigation. After reading the actual law on the subject, it is apparent that he would have needed to recuse himself whether or not he had met with a Russian ambassador. It was his position with a political campaign subject to investigation that was the determining factor.
On the subject of recusel, it is interesting to note how many time recent AG have recused themselves.
Reno - 2
Mukasey - 2
Gonzales - 2
Ashcraft - 3
Holder - 4
Lynch - 0 ?
Sessions - 1