(And damn you, 2017.)
I think I remember hearing on a radio interview (so many years ago!) that ELP had presented a demo tape to Copeland in the hopes of gaining his blessing to release the recording - but they omitted Emerson's wild keyboard solo from the demo, fearing it would bring a sure rejection from Copeland. After hearing the tape, Copeland turned them down - saying they hadn't done anything original with the piece! Upon hearing the whole recording, he gave his approval.
At least, that's how I remember the story. But memory is a fragile thing.