When well, I cycle and seven miles is probably around half an hour for a reasonably fit cyclist on roads without too many hold ups. BJ would therefore have around an hour's exercise for a return trip of 14 miles.
A younger, fitter cyclist could easily cover far more distance (probably double) and real oldies perhaps half, so age and fitness come into BJ's equation. I assume his fitness is the former.
BJ (and I am not a fan at the moment) could not have cycled in the nearby parks as cyclists are banned from most areas in them.
I agree there should be better guidelines and clearer information, much of it thus far is open to interpretation or misinterpretation but a cyclist can obviously travel further than a walker.
The issue for me is the problem of accidents:. any mishap requiring medical treatment puts more strain on the beleaguered NHS.
In essence, I don't have a coherent answer! Yes, cyclists will travel further, yes, they could have an accident but so could a dog walker, tripping over dodgy paving stones!