The scientists will have presented their evidence and advice. It is the politicians and advisers who will have turned that into guidance for the country. A scientist didn't write "stay at home, protect the NHS, save lives", even if they will have been thinking alone those lines.
As I understood it, Cummings was initially sceptical about lockdown policies until he saw the early- to mid-March modelling, then quickly became a hard advocate of lockdown, to the extent that he fought against early relaxations of it. I imagine it will be tricky, now, to find the source of this as it will have been buried by the last weekend's news, but my impression of Cummings from the last month is that he's been "on my side", so to speak. This undermines all he has (apparently) fought for and it is astonishing that he cannot see that.
I think it was mozz who said this elsewhere, too, but for my part I would be content to see him merely apologise, rather than necessarily resign or be sacked. Admit that it looks bad, admit that appearances count at a time when holding the public's complete trust is vital, and simply show some basic human decency. It may now be too late for that, which shows even more just how badly this has been misjudged. An apology, or something that was at least vaguely lacking in arrogance, right from the start and this could have gone away fairly quickly.