Under normal administrations, yes, but this is no normal adminstration
Nor, possibly, was this ambassador doing what ambassadors normally do
which is stay out of, at arms length from, or at least maintain plausible deniability, of covert CIA operations intended to end run Congress and other parties such as Russia
Once an ambassador becomes an active part of a military or CIA operation, all bets are off. He jeopardizes his diplomatic status and immunity as a “non combatant”..as the al Qaeda combat milita demonstrated
Note that the “we disavow all knowledge” card has already been played by Biden among others, including Hillary, along with the “some adult has to step up so I take full responsibility” card
Yes it has, it just is not working in this situation. I think you are making good points, but they do the current administration no good. They all add up to incompetence, indifference, or misdirection, all of which are bad for the current administration.
The speed and volume and breadth of communication available on the planet today make the "disavow all knowledge" card very difficult to play.