More power to the Rabbi for not deleting it.
(A remark from a respectful and appreciative heart.
It seems to me that Your Honor has remained an irritable Hazon-Ish type, and tends to be stringent even where there’s no need.
At the end of the day, every question should have the presumption of being a real question until proven trolling; it seems to me that with the Rabbi every question has the presumption of trolling until proven otherwise.)

And now to the question.

People sit at home and see or hear especially harsh things, and sometimes outright spreading of poison and baseless hatred toward a state official level (which by definition represents the people, or at least most of them), and sometimes not only personally toward that state official level but sometimes also toward sectors of the public who, according to the best of their conscience, chose that same leadership.

And I’m not talking about ordinary criticism, nor about things said out of pain, because one does not judge a person at the time of his suffering, but about the spreading of actual poison.

A kind of exploitation of spilled blood to spread something truly ugly.

The question is how to respond to children who ask, and rightly so—their senses have not yet grown dull.

On the one hand, the heart is full of compassion for people in their grief, and they too are part of the price we pay on the road toward realizing our great purposes as a nation, and we must contain it.

On the other hand, there are dangerous boundaries of baseless hatred and poison that one should not tolerate, certainly not when this is exploitation of the blood, when it is directed at a figure who deserves respect by virtue of what he represents, when it is directed at someone who chose to come and pay his respects even though he could have refrained from coming (a phone call, a letter of condolence, and the like), when it is exploiting conduct that goes beyond the letter of the law on the part of the visitor, when very often it also really does not represent the worldview of the fallen person, who was at times loving, gentle, wise, and knowingly took on the risk and its consequences willingly (and happily?), (though sometimes it does reflect the kind of talk the reviler hears from his rabbis in the yeshiva where he studies, and the like), when it seeks to erode the remnants of the nation’s cohesion and the consensus around bereavement and the price of blood.

After all, we were exiled from here 2,000 years ago because of baseless hatred…

(Of course the question is not specifically about one case or another that can perhaps be judged favorably, such as a young person whose eyes have not yet been opened, etc., but a general question about boundaries that lately are being crossed again and again. And the political position of the mourner doesn’t matter either, but rather the principle of the boundaries of tolerance on a subject that seemingly exists honorably within broad agreement, and there are those who exploit that in a disgraceful way.)

What do we tell ourselves? And the children?
Is this tolerable?
Should we contain it?
Or say: no.
This is outside the bounds of tolerance?

Asked respectfully and not trolling.
I would be glad for an answer from the Rabbi.

It reminds me of a similar question.

Democracy and tolerance of diversity.
What is the rule regarding a party that aspires to abolish democracy and the diversity of opinions? (For example, rule by Jewish law in an extremist and violent interpretation.) Is it fit to run? (The law decided no, because whoever rejects a Jewish and democratic state cannot run; the question is what would be the case without that law.)

And similarly with bereavement in the name of Jewish unity—we contain a lot.
Someone who exploits precisely that in order to harm the remnants of Jewish unity—should we allow it?

Is this trolling again? Where have you seen me apply a presumption of trolling? How many questions on the site were answered with the response that they were trolling? There isn’t even one percent. If your own questions are answered that way (I don’t remember), it would be worth examining yourself.
As for your actual question, I still don’t see what the question is here. There are different cases, and each one requires separate discussion. You yourself answered your own question: if in your opinion someone spoke improperly, you can contain the pain and still respond to what was said. The fact that the speaker is from a bereaved family does not mean he is right, nor does it mean one cannot respond to him. The response should be given with taste and with understanding of the speaker’s situation. I don’t know what more there is to say here, and I don’t see a concrete question that can be answered.
The case that prompted the question is the treatment of Bennett by the sons and family of that Border Police counterterror unit officer who was killed. What exactly do you want me to say about that? One certainly may respond to them and say that they are being incited and speaking inappropriately, and one can preface that by saying that one understands the pain, but pain does not justify improper speech, surrender to Bibist incitement, and certainly does not mean they are right. There is no impediment at all to saying all that to them, and I don’t see any dilemma or question here.
By the way, speaking of trolling, your prefatory remarks about the officer knowing where he was going are completely unrelated to the question as you presented it. Therefore, in my opinion, it is indeed trolling. You wanted to protest something or express anger about some phenomenon, and you presented it as a question.

As for democracy, that is an entirely different question.