I am of the opinion that “No officer may qualify as a candidate” means officially being selected as a candidate for office. Not campaigning in hopes of being the candidate. Not receiving funds for that purpose. Not publishing a book or otherwise generating publicity. If DeSantis becomes one of the Republican primary candidates then his resignation would be required. It certainly is not required at this time.
Correction. To qualify means the proper paper work and fees have been made. My mistake. It is still an official process outlined in statute. It does not mean being selected as the candidate.