Yeah the original topic is about displaying credentials like CCRN,PCCN, CSC etc. on badges as a nurse.
The Ph.D. has earned him the right to be called Doctor, he is a doctor of philosophy, after all, doctorates are not limited to MD or DO. Although in this case, it's a gray area where the circumstance and location are factors where one might easily think of him as an MD or DO. Although is he functioning within a scope of being an NP?