Deadliest warrior is (like mythbusters) science-ish entertainment, not actual science. Comparing the effectiveness of the AK-47 and the M-16 is subjective, and lends itself to a science-ish comparison. Does the environment require accuracy or distance to target? M-16 is preferred. Is the weapon going to be operated in non-urban environments or for extended periods without opportunity to field-strip and clean? Advantage AK. In the haphazard melee that Deadliest warrior presents, I’d lean toward an AK only because of its “spray and pray” feature.
Bingo! You have identified the key problem with this show. This is why the Taliban "loses" in this episode--because of the nature of the battle. The same thing is true of the Green Beret vs. Spetznaz and Spartan vs. Ninja episodes. The ninja is forced to fight a Spartan hoplite in an open fight. At the end, one of the ninja team members then said something like: "well the ninja in real life would have run away and then come back later to kill the Spartan in his sleep." And that was my point.