Quoted from desertT1:I sort of see it that way too, why file this now, if ever? Public Domain titles seem to be one of those "just keep it quiet and don't use previous versions that are protected" things.
As you mentioned, licensed IP would give you exclusive/non-compete rights, and original IP isn't exactly high risk for c@ckblocking from another company releasing it before you. All are a little different, but if anyone is uncertain enough, then make sure you are really close to revealing before you file or you will ruin your reveal. If that's important to the company that is. Maybe AP doesn't care, but OK hasn't even started shipping yet.
A small company like AP might use filings as an indicator of enthusiasm among the community. One failed pin could be the end, so a surprise reveal might not be as important. Stern can have a surprise reveal and the pin could flop. Wait a few months and they are guaranteed to have another surprise reveal.