Actually the "immediate legal excuse" is more to do with encouraging walking and cycling as modes of transport in the context of a pandemic where there's likely a benefit to keeping levels of crowding on buses and trains down as much as possible.
So pandemic emergency provisions have been used to hurriedly implement LTNs to reduce bus crowding? Yet just a few posts back you proposed people take the bus to get their child to school, a 15-20 minute bus journey rather than their previous 4 minute drive, 4 times a day.
Of course you did, the script has always proposed take the bus as an active travel ingredient, recognising that walking and cycling aren't appropriate for every person or every journey. And you're right, they will.
Insiders will hopefully walk or cycle to schools, the physio or wherever as replacements for driving within local streets. If they don't they're advised to use a bus. Their inside-the-zone motor journey must evaporate, though of course they'll still need to get there and back. So in the longer term, December say, what proportion of previously school run adults are going to walk under the bridges 4 times a day, every day? For every hyperlocal journey that isn't walked or cycled and hasn't conveniently not been made at all, there's going to be displacement onto the perimeter and through roads, either by car or by bus. The same is true of journeys further afield, for non cyclists the only way to make the journey other than their car is the bus.
Of course some journeys have to be made by vehicle. Deliveries, Uber, trades, disabled, ferrying stuff won't evaporate much at all, and they'll all be forced back and forth round the perimeter as well. Perimeter and through roads will take all the pressure and clog up further, leading to more idling fumes and slower buses.
Future schemes on both sides of Brixton Hill will funnel into exactly the same road and bus pinch point at the Brixton crossroads..
So as a policy to concentrate pollution on the main roads and increase pressure on the buses this should all work well.
Is that really the most appropriate pandemic response?