his mom is a cinnamon pearl pied
If he has a visual pearl parent he is definitely split to pearl.
The pearl gene isn't the only thing that can cause ghost pearling however. The "spot gene" apparently causes ghost pearling on the wings of adult males, even though they never had pearl markings on their wings as juveniles. I've got several males with ghost pearls who don't have the pearl gene. There may be other things that can do it too.
I've started wondering whether it's actually related to the pearl gene at all, or if these markings are actually controlled by a different gene and it's just coincidence and our own expectations that make us think it's related to the pearl gene. I recently found out about a mutation in lovebirds called marbled that is somewhat similar to ghost pearling. I wonder if maybe we've got this same mutation or something similar to it in cockatiels without even knowing it.
Marbled lovebirds, from the Lovebirds Compendium by Dirk van den Abeele:
There's a marbled mutation in parrotlets too. All parrot species have a lot of the same genes and they get the same mutations. It's entirely possible that cockatiels have a toned-down version of it.