The SEC is actually who dictates the upgrade in the event a company meets the threshold for amount of shareholders and assets. I know of no penalties or hidden costs given by the OTC for not upgrading from a Pink company to an OTC reporting company because once you are reporting and the SEC threshold has occurred, the upgrade is automatic. There's nothing that I've found on the internet about any hidden costs. Do you have a link to these costs? As far as I'm aware, OTC is very transparent and upfront about their costs.
The number one reason, in my opinion, that Nanologix doesn't uplist is because they don't have the money to do so nor the assets required to nor do they meet the OTC qualifications to do so. Doesn't have much to do with short sellers because 1. Nobody is shorting NNLX and 2. If they were, they can't be responsible for the small revenues and asset value the company has produced; only management is responsible for that.