Intent doesn't matter to the person in the other car, who likely is relying on your behavior to some extend to understand traffic ahead. If your driving seems like a brake check and brings in all of the unsafe conditions associated with brake checking, then it's a brake check.
"I require every other human driver to be driving correctly so that my AI-car may drive unsafely" seems like a bad bet. I'd also imagine that, if as a human, I just slammed on my breaks for no reason on the highway, I would be found to be at fault for an accident assuming the car behind me wasn't directly tailgating me.
I suggest it's better to compare a given AI with humans in terms of fatalities caused per million miles driven. If an AI performs a little better than humans it should be legalized and if it performs dramatically better than humans, it should be mandatory.
Of course, this is where we need more data and greater transparency so we can answer these questions.
You're putting a lot of words in my mouth and assuming I'm against working on AI driving because one person might ever die. All I'm trying to point out is that it's pretty worrying to have a system that could cause a highway-speed accident because of a well-known and decently common bug. I'd be equally worried if it came up that some other decently selling model of car would randomly have the ABS system engage.
I wrote my OP here because the parent poster was casually talking about "not really break checking people" as if that's just normal behavior that's a part of R&D, instead of an AI accidentally emulating dangerous aggressive driving patterns that FSD is supposed to do away with. I'm not trying to ban FSD research or anything. I want this improved! It's just scary when people excuse dangerous behaviors by FSD systems because it's otherwise safer.
The other issue is that more data and greater transparency are both not things Tesla seems to have any interest in providing anyone, so while this may get fixed, it's not really pushing the industry forward all that much if no one other than Tesla is going to benefit. There's plenty of mentions in this thread of this sort of issue happening on other cars and adaptive cruise control systems that could benefit from an improvement for the betterment of all drivers, but instead "not breakchecking people" is going to be a unexplained feature improvement in some FSD patch probably.