Not often i agree with him, but i think he's got this middle seat issue absolutely bang on. The only way round that would be to increase prices to cover the empty seats, but then that'd likely mean that the planes wouldnt be [66%] full.
It's all a piece of bluster to make people 'feel' better about getting on an aircraft - but keeping the middle seat free would have no noticable benefit.
If the government wanted to kick start aviation, and avoid nonsense scenarios like this which would kill the sector, the only solution in my mind is to find a way to test passengers before they travel to the airport - almost like having a test 3 days before travel then self-isolating until the day if you are proven not to have it. You could have a little stamp that goes in your passport or similar to confirm.