I started skin picking when I was a child. Around the time my OCD was diagnosed. And growing up with it, it becomes such a thing instilled in the mind and it takes a lot of time and care to, not RID of it because that's setting up a goal that can end badly, but work with it.

I would pick my hands, my arms, my scalp. My mom purchased soothing creams so when I would feel like picking, I'd go for the cream instead. And that helped a lot because I was eight then, I am now 23, and I still go straight for the creams. And it isn't a bad habit, it does ease my anxiety loads.

When I began puberty, I wasn't particularly struck by it. Annoyed mostly, and my mom reminds me I was an anomaly with that. The one thing it did to me was heighten my OCD + Anxiety and Depression (what a mess of hormones). Which then lead to more skin picking, then me ripping out my eyelashes and eyebrows. I was not medicated until I was 18, so a lot of this was dealt with my mom working to make the house a no stress zone. If there was decreased stress, I was less likely to pick, etc. And it not only benefited myself, but my two siblings as well. I think making the home as stress free as possible, or dedicating an area for relaxation, is really important.

As for the concealer question; I don't think it's inappropriate. Makeup is not just used by women. And honestly, if it eases his anxiety any, then I see no harm in it at all.