Yeah, the tab at the top, which is currently up, folds over when closed to protect that end as well and as you say adds an air cushion there as well. Between that and the laptop being suspended inside the white box by the plastic tray, it can probably withstand a fair amount of abuse by careless handlers.
It is a little odd though that the outside box does not say “fragile” or “handle with care” or have any indication that there is a fragile device like a computer inside, other than the Lithium Battery label. Though I am fairly certain it would not make a difference in how it was handled if it did.