As I understand it a company has to file directly to the exchange specific financial data and attestations every quarter by a certain deadline date to stay on-side.

I do not know how onerous of a quarterly task this specfic kind of reporting is for a company like Zenith.  It is commonly done by many very small companies.

I suspect that its more a matter of whether there is a 'will' to have a market listing vs the 'ability' to qualify for one.