'The Machiavellian' shapes Machiavelli, and not falsely.
Perhaps if Machiavelli had written the Prince for himself --merely to clarify his own thinking, as Marcus Aurelius claimed of The Meditations-- we could say that the use of "Machiavellian" has now strayed from some original, true designation. But Machiavelli did not write it for himself, he published it.
Trying to look at it as a consequentialist would, I'm amazed at how many of those worst characters in modern history, those who most typify 'the Machiavellian,' actually did read Machiavelli.
He set out to write an innocent consequentialist morality with the hope that it would aid in the liberation of his homeland, yes. However, once his work entered into the language at large, it truly became something different.