They probably want to avoid anything that sounds like it might be Jewish, so Aaron is out. This is not because of direct anti-Semitism, but because of the fear of it. Avoiding such words avoids the subject entirely. (Ironically, the Semitic origins of the word “Alphabet” aren’t as obvious.)

Aardvark is too alien and weird. Also, C-levels are deathly afraid of varking too aard.

Abacus might have been a better choice, but it doesn’t come with the infuriatingly tantalising closeness of one or two letters’ distance.