They are still for characters only. Technically you could make 5 or more skink chiefs with horned ones I think since the FAQ said they do not count as magic items, and have that as a unit. I think they would still need to join something else first and it wouldnt be a very effective unit.
Frankly, unless running characters solo, Horned Ones are not worth it, as A Scar-Vet (say) on one with unit of COC is still having to roll for stupidity.
Although horned one aren't magical the rules on selecting magic items still apply. Only one horned one per army, uses the character's magic allowance and prevents another item from the same category from being taken by the character.