Don't worry, it's not his. It's Gracie's. And, he'd only picked it up because Gracie dropped it and he was mildly concerned that the "baby" had been injured. When he realized it was, in fact, a doll, I think he was a bit disappointed with the whole situation; and promptly began playing with it like I'd expect any boy to do. He swung it around wildly and flung it as far as he could until her little plastic head thudded against the bench. Wahoo, look at her fly!
P.S. Poor Gracie cowering on the slide off in the distance. Doesn't she look afraid that her poor dolly is going to be maimed in this awful torture? Don't worry, she didn't cry.