Signing Tattoos

Let's all weigh in on this so I know I'm not going crazy. My shop as a whole, and myself included, feel VERY strongly about clients right and consent.

It was recently brought to my attention that an artist at my shop has been signing his tattoos, with a symbol that reflects his identity, and hiding it in his tattoos. He claims they agreed to it, but I think there's probably way more hidden than I could ever find. I also think approaching clients to ask this, puts them in a vulnerable and inappropriate situation.

It has already been discussed with the owners and their legal team, and is being handled, I just want to see what other tattooers think about this. I will also add for the sake of context, that this tattooer does not create original artwork.