In any public statement about its products or services, it’s to be expected that a private company will present information that frames those products and services as favorably as possible. Any commercial or advertisement is an example.
Whether the Postal Service should engage in such a practice is another matter. Though it’s supposed to operate in a “businesslike manner,” it’s fundamentally a government agency whose vaunted trustworthiness would make the transparency of operations and complete honesty of information no less than core values.