The special counsel appointment is a very dangerous thing. Giving a prosecutor unlimited resources and power to dig into somebodyís background is irresponsible at best, and violates the Constitution at worst. Thatís especially true when thereís no oversight or real check on power.
If Cohenís office was raided due to potential campaign finance violations related to Trumpís extramarital affairs, that has absolutely zero to do with collusion with Russia. If Rosenstein isnít reigning that in, ive got no problem with him being fired.
I donít know much about the history of the special counsel and the propriety of its use under Nixon, but in terms of due process Iíve been disgusted by the fishing expedition that both Ken Starr and Mueller have been allowed to undertake.
But if in the process of investigating the Russian collusion the special counsel uncovers something that needs further investigation that has nothing to do with the original investigation, he has a duty to report it to the Attourney General, or in this case, Assistant AG, and have them determine what to do.
From what I have read, this is what Mueller did. Rosenstein then forwarded the info to the Southern NY office of the FBI who proceeded with the investigation from there.
I don't see, if this is what happened, what there is to be upset about unless the Special Counsel purposely went looking somewhere they shouldn't have, doing everything possible to nab the president in a partisan fueled hit job. That simply isn't Mueller's history.
I think the more likely scenario is Trump is very dirty and has surrounded himself with dirty people and has left a long trail of evidence proving thus and that Mueller is uncovering it.