it’s not an appeal to authority, if the choice was his, not ours, to begin with. Tons of acronyms have letters that are pronounced differently. It could be arbitrary because an acronym is its own separate word.
Divers don’t dive oonderwater with their scuba gear. And when they take a camera with them, they don’t get the pictures saved as jaypheg files.
The choice can be arbitrary. Since it is, the creator gets to decide. Like whoever discovers a new species of creature gets to name it whatever they like.