Given the context around that line, I interpret that as applying to their actual Mac applications that deal with usernames/password/hostnames, especially since the sentence that precedes that is

> Except as described above

And further up there is a carve-out for Playdate logging.

They also don't really need to send out your username for the API call -- they already know who you are because your device is tied to your account.

I do find it surprising that there is no way to not participate in leaderboards.