Johnson's bumbling is all part of the act, it will be a ruse to turn the spotlight away from his incompetence and onto the umbrella, his speeches have always been opaque and unclear, see Trump for another that makes no sense and punctuates his nonsensical phraseology with key words that resonate, Family Guy parodied the style perfectly with Lois Griffin's mayoral campaign.
Johnson has no real interest in Brexit, Covid or real politics, they are all simply tools to carve out his own brand and celebrity, I think it's the attention rather than the power he craves which is why he is all over the place in terms of political ideology and policy.
Whatever the case he is and will forever be the man least suited to the role of Prime Minister who has ascended to that position, his popularity and the acceptance of his incompetence by so many show's that as a nation we have never been less aware of the realpolitik and what constitutes proper governance.