The Washington Post article also said, "...In hindsight, the letter seemed a rejoinder to President Bush's assertions that key congressional leaders were adequately briefed on the expanded NSA program and to his intimation that they did not seriously object."
They were adequately briefed. Rockfellar was too damn dumb to understand what he was being told and did absolutely nothing to fix that position. As for not seriously objecting. Yeah whatever, if you call someone who complains that they don't have a clue about what they were just briefed on, objecting.