Bolton's clearance is more than likely higher than that of the Senators.
I was told years ago by someone in the State Department that they routinely altered/redacted/stonewalled any documents to the Senate because they knew they couldn't trust them. OTOH, they also routinely shined them on, since they controlled appropriations.
On the killing hand, the Senators know they aren't going to get those documents. They don't want the information, they just want the issue. They figure the majority of Americans will only hear that information is being *denied* to their *representatives*.
Schizoids like McCain are right at home in DC.
They also leak them to undercut policies or people they don't like. Biden and Dodd have already received these documents or they have been told what is in them. The Dems figure they can't lose. If the administration fails to provide them, they continue the non-filibuster filibuster. If they recieve the documents, they use the information to kill the nomination.
BTW. I spent almost 30 years in the State Department.