Great episode!  A few etymological notes (because what else is a philologist going to comment on…)
The French traduction and traduire, if I’m not mistaken, go back to the Latin transduco, which at its root means “to lead across.”  This has a common ancestor with our “traduce” though the French don’t seem to use traduire in the sense of betray.
The modern French word for “betray” is trahir, which apparently comes from trado, the same verb that gives us tradition. As you all noted, we apparently used to use tradition in that same negative sense (I didn’t know that!).
The negative connotations of the Latin verb trado (from trans+dare, to give over, or to give across) go back a long time.  Cicero apparently uses the word to mean treachery, and the Donatist controversy in the early 4th Century was sparked by a group of traditores, that is clergy who handed over sacred books.  That said, it wasn’t exclusively negative. 
You’re notes one the Greek παράδοσις (paradosis) were spot on: it’s a very similar in formation to trado. One further note: though we have a critique of tradition in the Gospels, they’re not at all negative in the Epistles.  One thing that annoys me is how the NIV84 handle the word is that they use different words depending on whether a paradosis is good or bad.  So when Jesus castigates the Pharisees, Jesus attacks them for relying on the “traditions of man.”  On the other hand, when Paul instructs his churches to “hold to the paradoseis I gave to you,” the old NIV84 translated paradoseis as “teachings” rather than “traditions.” Fortunately that’s been rectified in the update.