The USCCB (and its predecessor, the NCCB) is not really known for having strongly-worded or well-worded documents. Their documents also do not have the force of law unless approved by Rome. The document in question says:
In order to be properly disposed to receive Communion, participants
should not be conscious of grave sin and
normally should have fasted for one hour. A person who is conscious of grave sin is not to receive the Body and Blood of the Lord without prior sacramental confession except for a grave reason where there is no opportunity for confession. In this case, the person is to be mindful of the obligation to make an act of perfect contrition, including the intention of confessing as soon as possible (canon 916). A frequent reception of the Sacrament of Penance is encouraged for all.
This document
must (not just “should”!) be interpreted in light of ACTUAL universal law. Regarding the fast, Canon 919 must be read, which I showed already. The document also says “
normally should”, meaning that fasting for an hour is the norm. This norm has certain exceptions, detailed in Canon Law. Canon Law says that a person who is receiving “is to” fast. That’s equivalent to “must”.
And as for the word “should”…
aux.v., Past tense of
shall. (As in “thou shall not commit adultery”)
- Used to express obligation or duty: You should send her a note.
- Used to express probability or expectation: They should arrive at noon.
- Used to express conditionality or contingency: If she should fall, then so would I.
- Used to moderate the directness or bluntness of a statement: I should think he would like to go.
Tell God that “not following a [not] should” is not an abuse! 
The wording might be ambiguous (which seems to be the
status quo for the past few decades), but we have other more authoritative and less ambiguous documents with which to interpret it.