I just think trolling requires some form of incitement leading to action by the victim. You post something inflammatory online, and get other people angrily posting back.

Making the t-shirt doesn't troll them, it doesn't get them to do anything. It's just a response to them, they publicly said he's a wanted alleged criminal and he publicly stuck his tongue out back at them. Now, if he made these t-shirts and then law enforcement tried to find him through his t-shirt supply chain, only to find that the t-shirts had been printed by the detective's mum's Etsy company, then that would be trolling.