I will have to respectfully disagree with you here Steven. :)
We are human, and any philosophy has to be filtered through the mess of a brain of a human. For me, the point of philosophy is not to leave it as some perfect thing to be admired on a pedestal. Instead, the point of it should be how well it can help a person deal with day to day problems.
All humans are flawed, some less so than others. Seneca, who is considered one of the greatest Roman Stoic philosophers, was also associated with the Nero regime and did not always live an exemplary life. Many philosophers, including guys like Socrates or Plato did some questionable things in their lives. We don't know much about Epictetus, but I am sure he was not a saint either. They were all living in slave-owning societies at the time as well.
I think the point of your essay is to say that the point of philosophy is not just the how (the stuff that can be classified as self-help), but also the why (the nature of the universe). Even under this, Thomas Jefferson would still qualify as a philosopher.
He was not a Stoic, or an Epicurean, or whatever philosopher, but a philosopher nevertheless. He was an eclectic, combining things from ancient philosophy (Stoic, Epicureans,...etc.), with ideas more closer to his time, guys like Locke or the Enlightenment figures.
Unlike Stalin, or Mr. Bean, he was an active student of philosophy, reading classical texts, but also more modern ones. What was special about Jefferson is that he didn't stay in the realm of the theoretical, but instead the crux of his work is how to apply things in practice. The result of that was the US Constitution.
We have to be careful not to put people on a pedestal, that is for sure. However, we have to be careful not to put philosophies on a pedestal either. We live in the real world, and the real world is messy.
If you apply too strict of a criteria of who is a "good" person, then you will be left with zero people. Former heroes like Jefferson or Abraham Lincoln are now being questioned, however the new heroes replacing them weren't perfect either. Martin Luther King was a womanizer, who it has come to light sat in on a rape. Shaka Zulu in South Africa was responsible for the mfecane. Everyone has their flaws.
That's why I am very sympathetic to what Plutarch did with his biographies of great leaders. He examined them with both their strengths and flaws. The idea was to read about them, and then apply the good things to your own life, and be wary of the bad things. While Plutarch is remembered as a biographer (and also a statesman), he was also a Middle Platonist philosopher in his own right.