First, understand that the relationship between UV lighting, calcium metabolism and reptiles is very poorly understood. In fact it is very poorly understood even in poultry - an animal that is easy to study due to it's short generation time and because so much money is available for agricultural research.
Nobody is "right" in this regard.
Some other comments:
Being nocturnal does not mean an animal does not have it's skin exposed to UV rays during the day. Flying geckos don't spend all of their day completely hidden under rocks, hidden in tree hollows, etc. They blend in with tree bark and certainly spend part of their day "sleeping" there. As such they will receive some UV exposure.
UV light is likely beneficial to lizards in ways other than vitamin D3 synthesis. So even if an animal does not need it for this process does not mean it is not beneficial in other ways.
Your peace of mind is what's most important. I have no doubt you could keep this animal with or without UV light. Go with what you're more comfortable with. Just don't let the "experts" dictate what your are comfortable with, at least when it comes to UV light.