They said in the article the parent was a barnvelder. Unless there are absolutely no other roosters in her flock, then I am fairly certain that bird is NOT a hybrid. It doesn't have any guinea traits at all and most guinea hybrids, in my experience, have at least one (although sometimes small) guinea type trait. That bird there just looks like a juvenile barnvelder that hasn't grown in all it's feathers yet.
There is a lot in the article that is incorrect. Mutations don't occur from hybrid crossing.