I agree with most of the points you made, and I was also surprised by the outcome. However, I would like to add a few thoughts:

• I wouldn't say that Tegmark and Bengio really "lost". As you mentioned, the difference could be attributed to randomness, particularly given the technical issues with the voting system. Moreover, in my opinion, the difference was too small to be significant, and noise could have played a role (the most indecisive voters may have chosen almost randomly).
• I don't think the way Mitchell handled the debate hurt her reputation, quite the contrary. There is a fine line between aggressiveness and confidence, and in most types of debates, confidence is perceived as a positive sign by the average person (not saying that this makes her arguments better), and she clearly displayed it.
• Not only LeCun and Mitchell argued with familiar heuristics, but also presented their viewpoints in a way that sounded reasonable. Saying that sci-fi speculation distracts from real harm sounds like something a reasonable person with common sense would say, even if I personally disagree with it.
• In my opinion, Tegmark and Bengio had stronger arguments (though I may be biased), but they could have presented them better. They had multiple opportunities to provide responses that, in my view, could have influenced the outcome positively. Here are a couple of examples:
  • At some point, Mitchell said that a superintelligent AI would obviously not misinterpret our goals, which could have been an opportunity to point out that the AI would indeed understand our intended goals, just not care about them.
  • Mitchell repeatedly argued that sci-fi risks distract us from real current-day harms of AI, which could have been an opportunity to explain why this statement is wrong.