If there was any doubt about how much sway Cummings has in Westminster now, you just have to look at the litany of Government Ministers currently falling over themselves on Twitter making tits of themselves excusing his actions.
Exactly what is the point in continuing with this? For now Labour should be going after the thing that Boris is now weakest on and that is the lifting of the lockdown. Boris's 'baby steps' are unravelling but most importantly its about looking to the future. People are still frightened about the future, at some point they will want their pound of flesh, but right now attacking the government about what one of its 'backroom boys' has or hasn't done is ludicrous. For the first time in ages there is a potential breach in what the PM can control from No.10.
Starmer was on the right track when he pressed Boris for a strategic plan for lifting the lockdown, because he, like we, all know the 'best laid plans'... etc. and 'no plan ever survives the first contact with the enemy .. and so on, it means this is the time when slip ups are difficult to control and to change direction. Starmer has to get a grip of his shadow front bench, like Boris has with his cabinet and start pulling in the same direction, not firing off at targets which have already passed by.