He isn’t doing this because he really wants anyone in Congress to investigate the matter (he can have that all done inside the U.S. Justice Department). He’s doing it to get all the Democrats whining about Congressman Nunes to shut the hell up.
What I like about Trump's operating style, is that you can never be sure exactly what he's up to. He's playing his game several steps ahead of everyone else, who are playing their same old, DC political games.
He manipulates the media and the news of the day by throwing out another bright, shiny Tweet object for the press squirrels to scurry after. He's a master at controlling the media conversation.
Playing offense and throwing the Russian bomb back into the Clintons' laps, is a perfect ruse to get the conversation off of him and back in the direction of the democRATS. Great deflection.
Good job in viewing this from a different angle than others usually do.