Re: "Cut the red wire..."
You might wish to have a safe method of disarming the bomb in case your own aircraft has to land again without using it
No, because if you have a method of disarming it - then so does your enemy. And from watching varuous documentaries on TV, it's clear that the Germans did booby trap the detonators in the stuff they dropped on the UK. So we had to develop various methods of disarming the bombs without triggering them - one of which was to physically cut a hole in the bomb and take the explosives out (IIRC it was steamed out and then shovelled up off the floor or something like that).
If you have armed the bombs and then can't drop them on the target (or any secondary target) - you simply ditch them in the sea on the way home. I believe a heck of a lot of UK bombs were dropped in a specified zone in the Channel - and there was a theory that Glenn Miller was killed when his plane was hit by a bomb being dumped after an aborted raid, but it seems that theory has since been debunked.