In Mick Wall's book "Run to the Hills" the writing and recording of the TNOTB album is described as a "mad, unholy rush", to the extent that they actually included two songs Steve didn't really like (including one of his own!) simply because they didn't have any time left to write anything else, and they had to choose the singles before they had recorded anything at all. So this gives some context to Steve's statement about the "guide lyric" that ended up not being replaced. The original omission seems to have come about in the wake of the confusion caused by the arrival of Bruce. Why it laid unnoticed and unaddressed for so long we cannot tell, but there was never any attempt to hide it (as
@mckindog pointed out earlier). And when it was brought to their attention, Steve's and Rod's, they 'fessed up right away and set about putting it right to the best of their knowledge and belief, which is entirely how I expected they would respond and I believe this response is the true measure of both their characters.