Sometime, Google employees also show this kind of attitude in their social life which makes other people hard to just have social interaction with Google employees.
Plus, Google's huge and has very few internal communication barriers --- nearly everything is open to everyone. So it's really easy to get into the habit of casually talking about internal products when talking shop.
Then you notice someone nearby who isn't a Googler, and you go oh shit and stop talking.
It may be usual and common for Google employees to do that. That doesn't make it excusable, and it's a pretty big reason why I, too, tend to avoid gatherings where I know it's going to be a bunch of Google employees. They communicate that they don't want outsiders around? I can oblige.