Original publicly stated reasons included respect for standing Presidents.
GHWB being dead means docs related to GHWB's administration can start being declas'd in a more expeditious fashion.
Q's been taunting the cabal with "Suicide weekend?" for a while, waiting for them to play the "this death [we totally didn't ritually kill him because he volunteered/is our puppet, wink wink nudge nudge] is too important to ignore" card.
Now they have, and it'll cost them.