Contra Byrnes on UV & cancer

In his recent LessWrong post, Some takes on UV & cancer, Steve Byrnes comes out against the "Public Health Orthodoxy" on UV. Among other topics I won't be addressing, Brynes claims that non-sunburn sun exposure does not increase risk of skin cancer, and suggests that people should aim to "wean off" sunscreen and develop a permanent tan. Brynes is wrong and his advice is dangerous.