As much as I would love to believe that this is a hint towards BLU, the shirt hints in the past have been way more on the nose. Batman "The Dark Knight" for Dark Knight. Scarlet (red) Witch (mage) for Red Mage. The fact that we're having to come up with major leaps of logic to say Spider-Man means BLU or SAM inclines me to believe that this is something totally different. Either a different classic FF job that none of us or thinking of, or a brand new job for FFXIV.
Either that or he's just straight messing with us.