It's important that he lives by a code

https://startrek.website/post/2086733

It's important that he lives by a code - Star Trek: Website

They always have excuses in the comics. I think the latest one of “the Joker has a super Joker toxin in his heart that’s released when he dies to turn whomever kills him into an even worse Joker” to be quite forced.

By the way, the Batman Who Laughs really overstayed his welcome.

That’s just what happened in one universe though, right? Neither Batman nor Joker know about that, or did I misunderstood?
In the next series “The Batman Who Laughs”, they showed that the mainstream Joker also had this failsafe too and no spoilers because the plot kinda builds around that.
Ohh I see. Yeah that’s a bit too on the nose then.