because some are on the list
We know for a fact that former Congress-critters have files on them—one name exposed in old litigation was former (Democrat) Majority Leader Mitchell of Maine.
It is reasonably likely that there are files on some of the more senior sitting members of Congress.
Of course most of them should retire anyway since they are so old....
That may explain why the younger members of Congress (both parties) are calling for full disclosure.
They would be thrilled to rise in the ranks stepping over the bodies of some senior citizens.
Oh but Dershowitz said no one currently in office is involved. Do you not trust him? (I do not. I want to see the evidence.)