
Are you imagining cyclists on such a busy route as riding single-file in a full carriageway lane to themselves?

If they'd been in a carriageway lane, there would probably either have been cyclists riding side-by-side and the barger would still have rear-ended someone AND put them sideways across the path of any following motor vehicle, or if the lane was wider, some cyclists would have been hemmed into secondary by motorists overtaking in-lane and the barger would probably still have rear-ended one of them.
My gripe is not with those imaginary demons of your mind - it is with dangerous road users like the barger. Although substandard, the cycle lane there is mostly an irrelevance to the downright crap cycling.