I'm not sure I agree, at least not for the reasons stated.
There are many reasons why VM might have sold for what it did and 'money' is only part of the equation. She would not have made the decision alone, there'd be good bankers and investors at the table, who'd have some insight if it was a 'stupid' move.
Greene might have been a great choice for Google if Google were ready for it.
It seems there was an existential struggle over some issues, particularly the Military Contract thing. I feel sorry for both Sundar and Diane because it's a very tough one: there are ethnical issues, but also cultural and brand. If a good chunk of G staff really don't want to have military contracts ... well it's going to be a problem. That said, some people might feel the opposite (!), i.e. America may have issues but ultimately is a force for 'good' or at least they provide the safe, open and fair means literally for Google to exist. I'm not making arguments here, just pointing to how thorny that one is.
And of course trying to change culture (Enterprise Sales, Customer Orientation, Service and Support) to a company that has none of that ... is going to be hard.
AWS and MS are infinitely more suited to it.
It may very well be a better decision for G Cloud to simply carve out a piece of the cloud that suits their natural advantages and dynamics, as opposed to trying to appease GM, Mondelez and Barclay's IT teams.