Let's trace this back to the beginning (https://news.ycombinator.com/item?id=32866019):

This is /u/xoa quoting from TFA:

> Hassan Shibly, chief executive director of CAIR Florida, tells The Verge that most people who are shown the form giving CBP authority to search their device believe that they have an obligation to help the agents. “They’re not obligated to unlock the phone,” she says.

Which he follows up with:

> Right, same as a police officer who asks if they can "look around" or "ask a few questions". They may certainly ask that. You may choose to cooperate. But in general you'd be a fool to do so, and you also may say "no". If they arrest you they were almost certainly going to do so anyway but now they have less to go on and with more avenues to challenge it, and if they arrest you over exercising your rights you have a strong cause of action right there. CBP agents may well ask people this sort of thing all the time, but that doesn't mean citizens must comply.

Note that the scope of the discussion has been broadened here. /u/xoa is comparing phone searches at border stops to 'police officer[s] who [ask] if they can "look around" or "ask a few questions"'. And it's pretty clear that this list of police actions is not meant to be exhaustive, just illustrative. There are other unspecified things that an officer could do or say that would be within the scope of what /u/xoa is talking about.

So at this point in the conversation the scope is both broad and ambiguous.

The next step is /u/xnyan quoting /u/xoa:

> Right, same as a police officer who asks if they can "look around" or "ask a few questions". ...But in general you'd be a fool to do so, and you also may say "no"

and following up with:

> This is not only a very naive take, its a dangerous one - people have been killed by law enforcement for doing what you are suggesting. Law Enforcement Officers in the US has what is known as qualified immunity. In practice qualified immunity means as long as the LEO says they believed they were following rules (even if they were not), then they can do anything they want to you (including kill you) with little to no personal consequences.

> In other words, you can say "No officer, you can't look around without a warrant", to which they can say "I see an object that may be a gun, and you're moving your hand in the direction of your pocket. Stop. I'm afraid for my life, I need to break your car windows and throw you on the street"

The scope of the discussion has now been broadened yet again. And again, the specific details of the hypothetical scenario described by /u/xnyan are obviously intended to be illustrative and not exhaustive. An officer could say different words under different circumstances and still be within the scope of what /u/xnyan is talking about. And again, the full extent of the scope is ambiguous because /u/xnyan has not said how far he intended his example to be extrapolated.

But the next thing that /u/xnyan does is give an example of what he is talking about in order to support the point he is trying to make:

> It's common enough that a LEO can publicly and slowly strangle George Floyd on the street, recorded and in front of others, and the only notable/unusual aspect is that the police officer was convicted of a crime.

And finally:

> Your rights don't mean shit to cops.

All this allows us to infer that /u/xnyan intended the scope of his comment to be very broad indeed. He is basically saying that the police in the U.S. can, if they choose, do anything they want to you at any time under any circumstances, up to and including taking your life, and there is nothing you can do about it.

This is the point at which you asked:

> > people have been killed by law enforcement for doing what you are suggesting.

> Can you cite any examples of this happening?

Well, yes, he can. And he did.

I understand that it was not your intention to ask about the "unrelated" example, but in context, that is the most reasonable interpretation of the words that you actually wrote because you didn't say what you meant by "this". In the absence of clarification, the antecedent for "this" in English is usually the most recent reasonable reference, which is to say, the circumstances being described by /u/xnyan in the comment you were responding to, which were very broad, and which included an example as part of the description.