[AndyJackson]

Since this is an exemption from the normal rule making process it is subject to heightened scrutiny. Any administrative body in exercising discretion must first have that discretion, must exercise it [accounting for all the facts in the matter] and must exercise it reasonably.

If it is an emergency affecting the health of all citizens equally, the there is no reasonable argument for excluding any particular group, at least not one so large as to obviate the intended effect of the emergency decree, and therefore in this case the agency has exercised its discretion unreasonably which invalidates the decision.

[bigbob]

The president doesn’t have the same degree of control over USPS as other parts of the federal government because it is an Independent Agency of the executive branch.

Thus he can only recommend, not mandate.