Congress has received many briefings already, and will be briefed again as soon as the current investigation is complete. Looks like they don't want right wingers using incomplete information to make misleading statements like they usually do
From your link
The Office of the Director of National Intelligence, which is responsible for overseeing all 17 U.S. intelligence agencies, issued a statement contrasting the representative’s remarks, saying that members of Congress have received “extensive, detailed classified and unclassified briefings … since last summer and have continued to do so after Election Day.”
“Last week, the President ordered a full Intelligence Community review of foreign efforts to influence recent Presidential elections – from 2008 to present,” the statement said. “Once the review is complete in the coming weeks, the Intelligence Community stands ready to brief Congress—and will make those findings available to the public consistent with protecting intelligence sources and methods. We will not offer any comment until the review is complete.
So, you think that Congress shouldn't be permitted to ask questions and receive testimony from the agencies about their assertions? That Congress should just take their word for it? The intel agencies should be made to give solid evidence that said assertions are backed up with something more than conjecture and assumptions.
It's pretty well known that the CIA is left leaning, and by extension it could be presumed that so is the NSA.
Let's not forget that the FBI is disputing the alleged CIA evidence. Just like most rational Americans, the FBI needs irrefutable evidence before stating that the assertion has any basis in fact.