That argument will be tested in court. It certainly looks like things are the other way around as of now.

Most non-profit employees receive their compensation in the form of a salary. If you need to pay "market rate" competing with organizations that offer equity, you pay a bigger salary. When non-profits spin for-profits off (eg research spinoffs), they do it with a pretty strict wall between the non-profit and the for-profit. That is not the case for OpenAI.