Ruddy when talking to Woodruff brings up two points. 1) The Mueller had been under consideration for FBI Director to replace Comey and did have one meeting with Trump about it and 2) Mueller’s firm WilmerHale has previously represented Ivanka, Jared and Manafort — however the DOJ ethics office has the option to waive the conflict.
One prominent expert on government ethics rules said Wednesday that lawyers entering federal service would normally be required to recuse themselves from decisions regarding individuals who were represented by the new official's former firm.
"It's a possible wrinkle in all off this," said Richard Painter, a University of Minnesota law professor and former White House ethics lawyer under President George W. Bush. "Usually, there would be a one-year cooling off period."
And Mueller according to WilmerHale themselves wasn’t assigned to any cases involving the Kushner’s or Manafort, also.
The co-managing director of Wilmer Hale told the website that Mueller did not play any part in the firm’s work on behalf of Manafort, Trump or Kushner.
So with that in mind, If the cases have been more than a year ago it doesn’t matter, and even it they were the issue can be waived by DOJ.
Besides Trump’s pick for new FBI Director Christopher Wray has far more devastating conflicts than this.