The Art of War does not take into account of personal freedoms of the masses/people since such concepts did not did not exist back then.
As for Machiavelli, he never advocated tyranny, but was simply one of the most astute observers of human nature that has ever put pen to paper since Aristotle.
Machiavelli wrote the book "The Prince", which was basically a handguide to the justifications of a tyrant.
You need to read more than just "The Prince" to pass judgement on Machiavelli. The Prince was a hurried synopsis of his greater works called "The Discourses". In the Discourses his explanations go into greater detail.
Many people make the mistake of thinking that Machiavelli advocated all of the things of which he wrote, which is not true. Machiavelli was an objective observer of human nature and politics. The things he reveals about them are unpleasent, but nevertheless true, and he was reviled for that.
Machiavelli was primarily interested in "good" government and how to achieve that. But to understand what is good in government, one must understand what is bad about it, so that it can be recognized and avoided. In "The Prince," (1537) Machiavelli stated: "In the actions of men, and especially of Princes, from which there is no appeal, the end justifies the means."
At its publication most understood it to mean (and still do), that it was o.k. to do whatever you wanted if you achieved your means. And if all you ever read was "The Prince" (or the cliff-notes thereof), that is probably what you think.
In fact, he was simply stating a fact that has been proven time and time again. If your end is good and results in good, the people will generally forgive the means used to achieve them. It was a statement of fact, not a moral judgement, which, unfortunately, he did not fully explain in "The Prince."
For example, he wrote in The Discourses: "It will consequently be exceedingly rare that a good man should be found to employ wicked means to become prince, even though his final object be good; or that a bad man, after having become prince, should be willing to labor for good ends, and that it should enter his mind to use for good purpose that authority which he has acquired by evil means." Is that statement arguable?
He goes on to say: "A well-regulated republic, therefore, should open the way to public honors to those who seek reputation by means that are conducive to the public good; and close it to those whose aim is the advancement of private ends." We could all agree on that, I think.
Machiavelli was maligned by his "political" enemies in life (to whom he was threat by way of his illuminations), and continues to be to this day by people who think they can understand him by reading a pamphlet titled "The Prince". Read all three volumes of "The Discourse" and his "Art of War" before you pass judgement. Then read Aristotle's "Politics" and "Ethics" to see the similarities.
"No reading is more necessary than that of Machiavelli; those who affect to be shocked by his principals are nothing but petty intellectuals posing as humanists." - Karl von Clauswitz, On War, 1832.
As for Sun Tzu's Art of War, the application of any military strategy text, written in any age, to private life, is a matter of interpretation. Going from the Macro to the micro. The military axioms of Sun Tzu repeat themselves in various forms in most accepted strategy primers from Machivelli to Clauswitz, from Patton to Rommel. They are universal observations of strategy.
Take the following observation from Sun Tzu: "To capture an enemies army is better than to destroy it."
Does that apply to corporate life? Maybe yes, maybe no. It might be appllied to say that it is better to buy out the competition than it is to destroy it, (re: Bill Gates). Who knows? It is subject to interpretation when removed from pervue of the battlefield.
Or take this quote: "All warfare is based on deception. Therefore, when capable, feign incapacity; when active, inactivity. When near, make it appear that you are far away; When far away that you are near. Offer the enemy a bait to lure him; feign disorder and strike him."
Is this applicable to the work place? Perhaps. First you would have to determine if you have enemies that are trying to do you in from the next cubicle. If so, then it may be useful. If not, it could be destructive. The same as applied to politics.
The Art of War is applicable in private life, but not in all situations. Anymore than it is applicable in all military situations. That is why good military leaders don't just read Sun Tzu. They also read Clauswitz, Jomini, Machiavelli, Napoleon, Rommel, Patton, Hamurabbi, and others. So you can see where the lines of thought intersect and diverge and can make better judgements as to which rules apply best in any given military situation. General truths and axioms are only that. They must still be interpreted to the specific situation at hand for them to have relevance and meaning. They also have relevent corollaries in private life, but one needs to be careful in their application. Those that think they can be used as general rules of conduct (and there are many) are mistaken.