The thing is the website is in English, so it does not target 7 billion people. It only matters what percentage of target audience can process the message, and it's targeting professionals, so not even entire 300 mil population of US. Basically I think about 300 mil and 7bil numbers are wrong in determining if it was OK to use US-format.

I am not saying you are wrong, I agree that spelling out November would make it clear, but just that the numbers quoted are not representative of who will see the site.