In the contest of this outage, the "Global Head of Customer Success" should absolutely be taking the blame for failing to communicate with their customers.
You can attempt to deflect the blame purely onto engineering side of things, as people in sales often to, but you are objectively wrong.
I have suffered long outages with vendors before, the key for me was always COMMUNICATION. They should be communicating with every customer impacted, they should be telling them on going progress, where in the queue they are, etc etc etc.
Trust me as someone that make purchasing choices and recommendations the length of this outage is not the issue, the lack of communications is. As someone that makes purchasing choices and recommendations I do not blame the engineering, I blame sales or "Customer Success" or what ever PR name you want to further deflect sales to be....
Without knowing Atlassian's org structure all I, an outsider, know is that engineering had an issue and remediation status communication has been lacking. If anyone should take "blame" it should be the bad engineering practices (usually a lack of funding or inability for upper management to prioritize engineering risk) which led to an outage of this magnitude and the status update mechanisms in place. Even then, I question how much better status communication would even get Atlassian given the sheer length of this outage, which is why I think the blame should ultimately land on engineering practices. Hopefully Atlassian learns from this but I'm afraid the damage is done. A SAAS system which takes this long to heal is unacceptable in 2022.