If they had a policy to ban German speakers from submitting code to OpenJDK, it would have the same effect. None at all, which is maybe the point. It's another tool to categorize submissions/submitters they find problematic.
First time you're caught, you are no longer a project contributor and your deceptive conduct will be forwarded to all other major open source projects with warnings that your code cannot be trustworthy and is a well documented legal liability. How's that sit with you?