No idea. But if you let your kid use your profile to play, how are YOU going to enjoy World of Goo?
You're allowed up to 5 profiles. Why does this line of technicality even matter?
Because of the absurdity of offering kids games, but disallowing them from kids profiles.
Is world of goo a kids game? I mean, it's appropriate for kids, but it doesn't seem to target them particularly. This adult enjoys it.
This is most likely lawyer CYA, rather than any real attempt to stop kids from playing games. Is it absurd? Yes. Is anyone going to have any issues with it? No.