Outside of an urban area, the whole legitimacy issue of riding bikes on a footpath (one where there is no road next to it and which crosses rural terrain) is a nonsense.
The argument made in that article is that it is for the saftey or walkers. Well if that's the case why are we allowed to ride on bridleways on which you are as likely to meet walkers as you are on footpaths? Come to think of it, if it rule is there to protect walkers, how come horses are allowed on bridleways as well?
The whole thing is just ancient bylaw rubbish that happens to serve the interests of the walkers and rule bound ninnies. As someone has justly pointed out, they don't have this distinction in Scotland.
Perhaps it's about time we reclaimed all rights of way?