Found some analysis on it:

https://journals.openedition.org/sillagescritiques/4840

“In my own correspondence with Kennard he suggested that the poem’s message is that “there’s more than one way to murder someone, and the narrator, in his vaudevillian, repetitive cruelty, is the real murderer.”1 So we are meant to see the moral shortcomings of both of the central characters, and the piece appears to make a case for moral relativism: the speaker’s moral pronouncements are comically undermined and the poem seems consistent with postmodernism’s refusal to construct a moral hierarchy.”

Also, this isn’t the full poem. There’s more, and it is really funny (and a bit bleak).

OP here. Not to get all EngLit teacher, but pretty much any instinctual reaction to art is valid. Perhaps the author wants you to feel slightly confused - as thats a common function of art (see crosswords/puzzles, murder mysteries, stories that start in medias res, magic eyes, postmodern novels, cut up art, or really any art that isn’t entirely linear and explained, which can include naturalistic drama if an antagonists’ motivations aren’t revealed until later)

Perhaps they want you to consider what it means to be a criminal, to observe and interact with a criminal, what it means to serve one’s punishment and the aftermath, what it means to be an ex-criminal, how we imagine our responses to crime (it seems like there’s a bunch of reactions in the poem: rehabilitation, activities in society, removing someone from a cycle, violence, verbal abuse…)

It could also be a reflection on how we use humor to cope — the speaker in the poem knows he’s (friends? accompanying? the officer assigned to?) with a murderer and yet jokes about it - a pretty human thing and an interesting concept for a poem

It also speaks to me of dystopic fiction or experiments in rehabilitation / psychotherapy in the past/present, and the media’s and society’s reaction to such.

Plus, I find it quite amusing even without deeper thought.