So far as I'm aware blameless postmortems don't really exist for project level failures. If I propose a new system, say a new load balancing scheme, it staffed and built and then is a failure as a system I am actually going to get blamed for that failure.
In theory Pichai took the blame but in practice that means nothing. On the one hand there were no job repercussions, on the other there was no attempt to break down the factors that lead to the errors and discuss what changes would be made to prevent similar errors. So not blameless or blamefull, nothing at all.
The same is true for directors and CEOs.