@joepie91 In general, yes. Full stop.
Depending on where you are located, you may still be legally required to publish counter statements and/or corrections if you operate something that resembles a journalistic platform. This depends on the local jurisdiction.
@yahe Right. But that's not what was being demanded here, so I don't know why you're bringing that into the picture.
The recipient said "stop". The Kagi dude didn't stop. That is really the only part of the story here that matters, and in that context I'm not sure where the confusion around an upset response comes from, because that seems pretty clearly problematic.