If by "They" you mean Apple, then they did not. As noted by jsnell, and properly attributed in the linked article, it was written by the National Center for Missing and Exploited Children
It's true that if you retweet someone else's message, then you are not the original author of the message. But Apple leadership vetted the letter and passed it around staff, hoping that their employees would find it as "incredibly motivating" as they did.