Intentionally recruiting, or aiding recruitment, seems like "material support" to me. But this is a teenager. And an 11 year sentence...
Today, a federal court sentenced a 17-year-old Virginia resident named Ali Shukri Amin to 11 years and four months in prison for supporting the Islamic State of Iraq and Syria, commonly known as ISIS. Amin ran the @Amreekiwitness Twitter account, which published pro-ISIS messages to a relatively small following, as well as directing followers how to make Bitcoin donations to the group. In one effort that proved particularly crucial to the prosecution's case, Amin arranged for an ISIS supporter to travel to Syria. All of Amin's efforts were conducted from within the United States, and there's no evidence that he ever took part in violent acts or intended to do so.