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.
OpenAI has always argued that the for-profit is furthering the aims of the non-profit.
Also employees can't get shares of the non-profit so of course they would from the for-profit arm.