A lot of the reporting is kind of fuzzy. However, I suppose one of the things is the nature of "ownership". The numbers say there are about 32 million outstanding shares. This article says that Schnatter's ownership is in the form of restricted stock units and options, but they're not aware of whether or not the resignation has affected that for him. He's still on the board. I remember when I was no longer employed at a company, I was required to either exercise my options within a specified time (might have been 90 days?) or they would expire.
https://www.investopedia.com/news/top-4-papa-johns-shareholders-pzza/
The company went public under the ticker PZZA in 1993. Schnatter currently owns 7,056 restricted stock units (RSU) and 463,879 options as of March 12, 2018, making him the largest shareholder. These numbers may be subject to change after Schnatter's resignation as the company's chairman.
In his case I'm not sure how he would handle this. I'd think that a lot of his net worth came from when he previously exercised his options. There's been no reporting of how many outstanding shares he owns. Also - I'm not sure he would be able to just exercise all of them at once and sell, because something like that would just kill the price.