A better analogy would be: You discover that all doorlocks of some vendor can easily be opened without the key, including your neighbors. So you tell the vendor. The vendor does nothing about it for 6 months, so you decide to tell everyone who has the lock instead so they can fix/change it.

Would that not fall into responsible disclosure? Maybe the definition I have is different

I would think that if you make an honest and serious attempt to coordinate with the vendor, it's responsible.

I think his point is rather that "responsible" is a weasel-word.

They contacted Google on August 22nd, 2016 and Google decided to do very little about it. At least we know there is a problem now and we can take mitigation actions.

It would be irresponsible and being a bad neighbor to post on social media about your neighbors door being unlocked at all ever, really.

But you might want to tell your neighbors housemates about it if your neighbor keeps leaving the door unlocked and they haven't noticed but you have. Or worse, if your neighbor is making duplicates of his keys and handing them out around the neighborhood.

The flaw in the analogy is that your neighbors door being unlocked effects nobody but your neighbor and their housemates.