The jobs need not align to their in-game guilds even if they match up with their classes. In fact, they may even represent a counterpoint to the relevant guild.

Conjurer = peaceful, calming and at one with the elementals, working with the moogles to preserve and balance.
Black Mage = violent & enraging the elementals' power with ancient rituals to prepare for war with the Garleans.

Thaumaturge = obsessed with death's power in the Arzanaeth Ossuary. And accruing wealth.
White Mage = obsessed with life's power in the Milvaneth Sacrarium. And "donations".

Thus, this spread could be plausible in the current lore.