A signature ability of the new Diabolic Dragon is its Diabolic Flames allowing it to deal spirit damage instead of fire damage with any of its abilities. However, despite the flavor text saying that this is because its flames are "imbued with the unholy power of Hell", it does not look like it mechanically sanctifies them as unholy. The jaws strike and Hellfire Breath were already unholy, and Divine Immolation not only already has the Sanctified trait but doesn't need Diabolic Flames to do spirit damage, but the other fire-based Innate Spells the Diabolic Dragon has are not Unholy or Sanctified and thus are not unholy when cast by a Diabolic Dragon.
I have two questions about this. First, why did this happen? Second, aside from making spellcasting Diabolic Dragons have a completely redundant cantrip in their default selections (an Ignition that can deal unholy damage would remove the need for Divine Lance), would there be any problem in allowing a Diabolic Dragon to sanctify its fire spells?