Why not, I grow all of my Mexican Pinguicula in 100% granulated peat moss, kept "WET", year-'round and I have no problems with them rotting, even Pinguicula gypsicola and Pinguicula laueana.
I am also a strong believer in propagation (very few of my Pinguicula are represented in my culture by only one specimen). So, presently many plants of each type are now growing in a variety of media besides peat moss.
Light is the answer. . . Pinguicula, especially Mexican species and hybrids definitely exhibit a different phenotype when grown with abundant light. With somewhat less light I have whitnessed gorgeous plants quickly revert to all-green, insipid forms --- though with abundand flowers (Perhaps a last ditch effort to reproduce due to non-optimal environmental conditions?).