The flipside to that, or at least how I first interpreted it, is that Hermes' disguise is flimsy and not especially tough to see through. He's an old god with a nearly non-existent following, so he's going to be a little out of touch. Like the MC says, "a 'deliveryman?' Really?"
I never felt like seeing the neon sign behind Jean that reads "by the way I'm Hermes" took anything away from his arc. His motivations were always the bigger part of the mystery. Whether or not you clock him doesn't really have an appreciable impact on the story up until the point that you/Asterion sock him.
Was this all just an excuse for that last sentence? Maaaaaaybe. Suffice it to say, I think Jean was handled very well!