Teaching requires empathy. A small application of empathy should tell you that no one in your audience will take your word for granted on this. This lack of trust could be very easily remedied with a single example: "cannot be dismissed as easily as you believe, because of some refuting point that wasn't brought up in any of the previous discussions, as you will also see wasn't brought up in any previous discussions".

I honestly don't see any valid reason to wait for a debate with komponisto in particular to provide this sort of evidence, either; which makes it sound suspiciously like an excuse for delay.

I think that is highly unlikely. Nothing you presented in your post here was new information to me (or to anyone else who spent some time reading the original comment threads and did some research of their own I imagine). I'm familiar enough with it to know where you've been misleading or selective. Unless you have some secret new previously undisclosed information to reveal in your debate I rate the probability of me changing my estimates for Knox's guilt significantly as pretty low.

Have you updated your own probabilities in light of the widespread disagreement with your position here? If so how?

Where was that specific point already addressed in previous discussion?

Here for one.

This CNN story covers some of the doubts around the handling of the bra and the validity of the DNA results:

Bremner says that evidence on the clasp is fundamentally flawed, like much from the crime scene collection, calling the work "Fellini forensics." "In the [crime scene] video, you can see it went from being white in color to nearly black because it got so dirty being moved around," Bremner said of the clasp, noting that tainted the only evidence that placed Sollecito at the scene.

Here's a source for the 'three unidentified individuals' DNA' claim:

The other key plank of the prosecution's DNA evidence related to a clasp severed from Meredith's bra that was found at the scene.

This was said to have Sollecito's DNA on it. But the defence has long challenged its evidential value because it was not recovered from the floor of the victim's bedroom until 47 days after the murder.

During that time, they claim, it was contaminated - an argument apparently supported by the fact that the rest of the bra did not show any such DNA traces.

That police could have missed the clasp for so long is also put forward as being indicative of the way in which the murder investigation was carried out. Video footage by detectives on November 3, 2007, two days after the murder, shows the bra clasp on the floor of Meredith's room, next to where her body was found. It had been cut from the bra she was wearing when she was attacked.

But it was not until December 18, when police revisited the crime scene, that they found the clasp at a different location in the room and finally collected it as evidence. It was then subjected to testing, which revealed microscopic traces of DNA belonging to Sollecito as well as at least three other unidentified people.

This DNA test result is central to the prosecution's case, because no other evidence links Sollecito or Knox to the room where the murder took place.

Emphasis mine. There is sufficient doubt around the DNA evidence to render it largely irrelevant in light of the prior probabilities for this kind of crime.