Single-word/Expression/Phrase for a name which pretends to be represent a thing that it is not. Example: PATRIOT Act

"The Patriot Act is anything but patriotic, it's a _____________."

Not the greatest example depending on your political view (sorry AuthRight), but I'm going off of the interpretation that the legislation named the USA PATRIOT Act purports itself to be something you would of course support if you were a patriotic person. Despite this, many believe the PATRIOT Act to be something entirely the opposite of patriotic.

So the term should describe something intentionally deceptive (perhaps to gain psychological influence). Homonym doesn't convey this intent. Malaprop describes a mistaken intent to a similar sounding word, but not a deceptive one. Contradiction in terms or Oxymoron describe a phrase that self-contradicts, but only one between the words it uses, not its external interpretation.

Single-word, phrases, and expressions all acceptable.

If you don't accept my earlier answer, you might use doubletalk, doublespeak, or doublethink.

doublespeak
noun
evasive, ambiguous language that is intended to deceive or confuse.
First recorded in 1950–55; double + speak, by analogy with doublethink

Doublethink
noun
the acceptance of two contradictory ideas or beliefs at the same time.
double + think1; coined by George Orwell in his novel 1984 (1949)

Quote

The Ministry of Peace concerns itself with war, the Ministry of Truth with lies, the Ministry of Love with torture and the Ministry of Plenty with starvation. These contradictions are not accidental, nor do they result from ordinary hypocrisy: they are deliberate exercises in doublethink. — Part II, Chapter IX

It might be described as a duplicity or as chicanery.

Duplicity = deceitfulness in speech or conduct, as by speaking or acting in two different ways to different people concerning the same matter

Dictionary.com

Chicanery = clever, dishonest talk or behaviour that is used to deceive people

Cambridge

Both terms are relevant to your example. The use of the word patriot is a duplicity that relies on the word’s having two meanings to its two different audiences. The use of the term is a political chicanery designed to deceive one of the audiences.