. . .tell him he can't take it out of the box and play with it?
My FIL suggested DS open the present at theirs this past weekend since we're not seeing them on Christmas. So DS (2.3) opens up a lovely Thomas Tidmouth Sheds, is absolutely thrilled, and immediately starts trying to open up the packaging. Of course I start helping him, and then FIL says 'shouldn't you take that away from him now and he can play with it at home'. Thankfully MIL stepped in (she rarely stands up to FIL).
He's bonkers, right? I could see if it was a messy art kit or some such thing for an older child, but DS is 2, FFS.