David Crosby can't carry Graham Nash's jock musically. It's absolutely absurd to think that the Byrd's third banana has any business in the Rock And Roll hall of fame when Graham Nash isn't there.
The Hollies belong in the R&R Hall not only because of Nash, not only because the group has never ceased to exist since 196-freaking-3, but because they were a great, great group. I could make a solid case for the POST-Nash Hollies, only considering their 1969 and later work, for being worthy of induction.
Put the Hollies in. And yes, Graham Nash can go along for the ride.