Don't be bonkers, of course Boris shouldn't be fined for going on a bike ride. He's exercising, on his own, and isn't socialising as far as I can tell from the reports.
I walk locally, I often walk 5 miles down the country lanes, sometimes 6 miles. Of course it's bloody local, it's in the lanes and footpaths in the lanes round our village. There are bike riders around and about. If I was on a bike it wouldn't take long to do 7 miles, probably 10 miles if I was out for my usual hour. So yes, it's local.
As far as I can see, those who have been moved on by police have either been socialising rather than exercising (sitting on a bench with a friend drinking coffee isn't exercising), or have got in their cars specifically to drive to a beauty spot which gets crowded if everyone descends on it, or else have been fined because they've not cooperated when police have asked them to move on.
That's very different from anyone going out for a bike ride.