You do it by simply pointing out facts - in this case both what we know AND what we (they) don't know. A reasonable person looks at it and says, "Yep, I made an accusation when I really couldn't tell". Some people won't react that way (I would note we haven't had a negative reaction from the original poster so I'm fine with that).
My task was just to point out the flaw in their comments. I had no problem with them bringing up the issue they had.
I'm not defending WT except about that one single accusation. It has nothing to do with other criticisms at all. As I keep saying, there are plenty of things to complain about without making stuff up!
Heck, I've anticipated some of this for when the TB actually ships. You know there will be people who have problems. I don't care how perfect they make it. I've compared it to App store reviews where some app gets hundreds of top ratings, but a handful of 1-star ratings. Seems illogical, so I read those negative reviews and what I most commonly find are people saying, "This app is worthless. It crashes every time."
Well, as in this case, if you have lots of great reviews (too many to be rigged) and it crashes for you, it probably isn't an app problem! So I mentioned awhile back that if people do find problems, they should report them, but keep in mind all the following (at least):
They just happened to get a faulty unit - there will always be some like that.
They have a problem with the rest of their system, not the TB. So maybe try it on another device before ranting.
Or the user did something wrong. Even something very basic - people who do customer service often make it a point to have the customer confirm it is plugged in!
Which reminds me of someone I tried to help. It was with an Apple IIgs which we both had. He knew I was a heavy user so he called me about a problem he had. I forget the details, but the computer would sometimes do weird things. On the phone, we talked for hours and did so for days, trying to figure out what was happening.
Finally I remembered reading something about the latest OS - that there was a problem with some accessibility things. I thought his problem might be that (I had long before made sure those were all off), even though he really had no need to have any on. Sure enough, he had some active so I told him to turn them off. He did and when I checked back a few days later, he said it was working fine.
End of story, except it wasn't. He called me back a couple weeks later saying the problems had returned! So I'm spending days again trying to figure out what else could be wrong. Finally I said to him, "You didn't turn the accessibility stuff on again, did you?"
And he had! I was ready to strangle him for wasting so much of my time doing such a dumb thing, but I was nice and asked him why the heck he had done that. His answer: "I think they're cool". Unbelievable. He KNEW what the problem was, thus the solution. He did it anyway and then so dumb he needed to call me to tell him the obvious!
So, yeah, you just can't get through to some people. But it doesn't mean you can't get through to any or, even if you can't with someone, that you shouldn't correct things.