Indeed, although their speciality is biology and not epidemiology, if they are to be believed it would seem that outdoor transmission is much more difficult. It's a shame the Richmond Park authorities don't seem to have read it.
In response to the - quite right and proper - message from the mods, we need to appreciate that our understanding of this disease and its behaviour is woeful and changing daily. "Official" guidance that has been issued has been found to be wrong and changed less than 48 hours later, so it's probably best not to get too hung up on that - I know police officers on duty who have received 3 x contradictory updates from Public Health England over the course the the shift on duty, and it is clear that all three could not be correct so my own thoughts are not to rely solely on government guidance as an avoidance tactic. The final decisions as regards the official guidelines is being made by politicians, not scientists, so may not represent is medically best for the individual. This is because politicians have to consider social, economic, administrative, financial and strategic factors whereas the scientists do not.
The only solid tactics that have consistently survived the ever changing scientific and political advice is being mindful of cleanliness and proximity, and with that in mind the OP's question is sensible enough. That said, scientific advice generally seems to be outdoor transmission is a very low risk likelihood [source: Prof J. Hellewell, The Lancet, February 28th 2020] when considering avoidance and tactics to reduce the transmission rates of the disease.