That's indeed correct!
I think it can be difficult to determine some mutations when other mutations are mutating the other colors!
Cobalt would imply he is a goldenface type 2, recessive pied with 1 dark factor. If he's not a cobalt, then he may simply be a goldenface type 2 recessive pied budgie. There's not really any reason to say he's blue unless he was also blue.
I mean, if he were paired with a blue hen, would he throw all goldenface offspring? (thus indicating he is a goldenface with two genes) or would he throw both goldenface and blue offspring? (indicating he's got 1 gene for goldenface and 1 gene for blue)
Not that it matters, but just something interesting to think about!