Nunes knew that the Dems would have tried to silience his information. It is that simple.

Austin Wright / Politico: Pelosi, Schiff call on Nunes to recuse himself from Russia probe

Notes:  You can't be more of a hypocrite than Schiff and Pelosi. There is nothing inappropriate with Nunes visiting trump,  except protocol would have had him present to the committee before the President.  At the time, that was the only criticism.  But the Dems love to major in minors while ignoring their own malfeasance,  and now they are trying to make an issue out of something that is simply a non-starter.

Update:  In case you were wondering:
The chairman of the House Intelligence Committee will not step down from the committee's investigation into Russia's interference in the United States presidential election, despite a growing chorus of Democratic lawmakers demanding he recuse himself. 
"Of course not," Nunes' communications director, Jack Langer, said when asked if the congressman would step aside. "They’re playing an absurd political game."
Nunes echoed that sentiment in an appearance on Fox News’ “The O’Reilly Factor” Monday night, saying in response to a question, “I’m sure the Democrats do want me to quit."

 The Hill,  here.