Not very hackery - but that was my prominent thought at the end of the article.
I mean maybe there is a tech point, that hair has historically been a pretty hard thing to model, so I'd presume hard to correct with a filter - so maybe its his luscious locks that helped sell the ruse (and I'll need to wait another few years to have my hairline pseudo-restored)
FaceApp also has a hair filter. You can change the color, make it curly, longer, etc.
In fact, it's popular in the transgender community. People can experiment with their new gender identity with a few clicks. You can transform a bald masculine figure into a soft model with long hair that retains some of your bone structure (and vice versa). Here is a tweet of one such transformation done on an actor using a stack of FaceApp filters: https://twitter.com/KaiqueBanks/status/1276185681660968961
Perhaps he's been using Christopher Walken's technique of pulling on your own hair for five minutes every morning to encourage blood circulation in your scalp? :)
