Yeah, this whole moment in DCAU future was SO messed up, but it gave the kids and everyone else an ice cold waterboarding dunk your bagged head of who and what the Joker really is. Even Terry never appreciated just how dark and dangerous and ..... highly unstable the Joker truly is.
Visiting this scene again, many years later, I can appreciate what was done, the entire true horror of it, as it was a trauma that not even the Batman fully recovered from.