Word that means using a falsehood which can be used as a weapon to advocate for and execute something else

Solution 1:

Difficult to find one word for all the three contexts. I first thought of fraudulent, but the second context does not seem to involve liability to law.

Maybe manipulative could work:

tending to influence or control someone or something to your advantage, often without anyone knowing it. (Cambridge)

But the -ing form of the verb to manipulate could also be used as an adjective:

manipulating

to manipulate means

to control something or someone to your advantage, often unfairly or dishonestly

• The opposition leader accused government ministers of manipulating the statistics to suit themselves. (Cambridge)

The politician, the Guinness adverts and Kyle could be said to be manipulative/manipulating.

Solution 2:

However this deficit did not exist so the politician was being Machiavellian

from TFD

2. (adj) being or acting in accordance with the principles of government analyzed in Machiavelli's The Prince, in which political expediency is placed above morality.
3. (adj) characterized by unscrupulous cunning, deception, or expediency.

(noun) - a cunning, amoral, and opportunist person, esp a politician

References in literature::

• "In fact, moral courage, integrity, steadfastness, self-esteem, etc., are among the major disqualifications to survive in this field, which is a full-time risk-free business that requires Machiavellian approach."
• "This also applies to Machiavellian supervisors, who are characterized by behavior that is inherently manipulative and deceitful."

From Collins

If you describe someone as Machiavellian, you are critical of them because they often make clever and secret plans to achieve their aims and are not honest with people.