After getting a better look at the background, this seems like a misstep.
Agreed that Luminous was not exhibiting behavior that seemed becoming of an admin (borrowing the terms of the db0 folks, they appear to be a bit of a "shit stirrer") but it doesn't look like there was any direct call to violence towards Kaplan, as this whole debacle seems to imply.
Luminous is no longer an admin, so I don't see why the defederation of anarchist.nexus needs to continue (given that its initial justification is already questionable). The main takeaway is that the admin team of Lemmy.world (or maybe just Kaplan, I don't know who all the admins are) seem to be taking criticism of Zionism personally...which to me sounds easily solved by simply not being Zionists.
So, if the LW team are not Zionists, I don't see why they shouldn't just come out and say so, but then I guess I don't see any other reason why someone would take a "death to Zionists" tagline personally.