It's the contents of the submission that are confidential, not the fact that they are submitting.

The contents themselves contain a lot of detailed information about the internals of the company including financials, revenue, ownership details etc... those details are what's confidential until the SEC gives its approval, at which point the public can then review the document.

I suppose they announced it because the fact that they submitted it would leak anyway.

I like your sense of humor

That's how you know it's purely marketing and they're not actually going public.