While Bulgarian law prohibits the production and distribution of pornographic material (article 159 of their Penal Code), enforcement practices are lenient towards softcore content. For instance, authorities tolerate the distribution of hardcore pornography in designated shops and even on television after 11:00 p.m., and softcore material is rarely censored.
Having a naked shower, posing naked without touching the genitals, artistic nude photography, beach nudity in naturism spaces, nude yoga or wellness content, sleep streaming naked, ... All of these fall under a very simple grey area that won't lead to consequences. He's not naked because he doesn't want. Simple as that.