I've assumed the name Trojan Horse was literally due to White Base's shape? You know with its head and four legs and all? I mean even the Feds went for the same equine naming convention with the ship class literally being Pegasus. Of course, Zeon probably could've chosen a less cool horse to name their arch-enemy but then again do you really want the cause of death for their precious prince to be "died during the battle against Federation warship codenamed Rainbow Pony" or something?