Based on the description in the article, they do sound horrible - little land mines waiting for one small step to send a cloud of death into the air.

Doing a bit of research, the Wikipedia article gives better information https://en.wikipedia.org/wiki/M44_(cyanide_device)

As I see it, they're basically an alternative to traps that don't kill quickly leading to animal suffering. They're designed to be really hard to trigger - the design was to have the animal put their mouth on it and pull hard.