If I understand right, this is a clarification (of sorts) to the standard of "true threat". Ken White covers a lot of first amendment speech issues and has a very good explanation here: https://popehat.substack.com/p/supreme-court-clarifies-true-threats

So. To the practitioner, or to the internet tough-talker, what does this mean? It means that the law of the land, at least 7-2, is that a threat is only outside the protection of the First Amendment if:

• A reasonable person, familiar with the context, would interpret the threat as a sincere statement of intent to do harm, and
• The speaker was reckless about whether the threat would be taken sincerely — that is, they “consciously disregarded a substantial risk” that it would be taken seriously.

To play devil's advocate, I think they're making a ruling that's analogous to the murder/manslaughter distinction. Murder (as is commonly defined) requires the prosecution to prove intent, whereas that's not required for manslaughter charges.

Obviously, it's possible to prove intent in some cases because people do get convicted of murder sometimes. They're saying the same thing here - it's okay to convict someone for this kind of speech if you can prove their intent was harmful. But the speech equivalent of "manslaughter", where you haven't proven intent, is constitutionally protected.

I can see ways that this as a good ruling, frankly. I can imagine situations where someone says something that can be interpreted as a threat but that really and truly was "just a joke" or some other such misunderstanding, and I would not want that to result in a conviction.