It may not be a strategy as such but some type of hard Brexit is due to happen shortly. In normal circumstances it would be hard to explain away the GDP hit and disruption to food and medical supplies etc.
If GDP is getting a large hit anyway and supply chains are in flux it would be easier for Cummings and Boris to hoodwink white van man that Covid-19 is to blame.
I think you are attributing far too much intelligence to people that are simply not very intelligent. The majority of politicians are as thick as shit, their ability to yap is like lipstick on a pig. Remember these effectively are the same lads who were telling us in 2006/7 that there was no housing bubble, prices would just rise forever, and then were caught by surprise when the market collapsed. They were wrong and the economy collapsed, imo they are wrong again and this time the economic damage will be far greater. It’s incompetence plain and simple.