Motherboard livestream discussing the article with a bit more info

In 2013, researchers at the University of North Carolina, Wilmington (UNCW) published a facial recognition dataset consisting of more than 1 million images of trans people who had uploaded videos of their medical transition to YouTube. The researchers used the videos without the explicit permission of their owners, and with the stated goal of training facial recognition systems to recognize people before and after they start Hormone Replacement Therapy (HRT).

Ricanek justified the experiment with an extreme and virtually impossible scenario: terrorists using HRT to avoid facial recognition and sneak across borders undetected.