It doesn't help to address claims nobody is making specifically dressed up to serve as fallacy. The normal claim is that police are killing black individuals unnecessarily. The claim you have offered is just that claim dressed in dramatic clothing.

Meanwhile transgender sacrificing children would be a falsehood wholly invented to smear a group that already frequently suffers violence and harassment and with the blatant intention of promoting and justifying further violence and harassment. The statement is in effect part of the process of harassing, harming, and ultimately killing people. It ought to be illegal in the same way that breaking into a home to commit rape is also illegal and liable to be punished more harshly itself than if the burglary was part of mere trespass.

I also take issue with drawing a line between a harmful lie like Sandy Hook and mass promotion of same in the fashion you have. Both should be illegal in the same way that starting a house on fire isn't any more legal than setting a fire that burns down whole housing development. The punishment may be harsher but its ultimately the same crime. It's also not a slippery slope AT ALL.

Passing on a falsehood that the individual knew or should have reasonable known was false is not at all like parsing the difference between police arbitrarily or unnecessarily killing black people. We can forgive trespasses where the truth is a matter of opinion, phrasing, or debate while trivially punishing people who blatantly lie or spread harmful nonsense.

If you don't know that dead children aren't crisis actors or forest fires aren't caused by jewish space lasers and you can't be educated you should probably be fined or imprisoned into silence so that the rest of society can move on.