Trust me, his intent was not nice. Pica doesn't like little chicks, he was trying to attack Pippin. I hope there won't be a problem when other pairs share the colony cage later... <__<"
Just keep a close eye when you introduce others. He'll be aggressive at first, anyway, since he seems territorial. Remove any birds that he injures. And if it gets to be a problem, you may have to move both he and his mate to a new, individual cage that's just for them. It means they take up a little more space, but if he's going to be a problem with others, it's better for all of them.