i did a little bit of reading on this, there are no other snakes on the island to eat the mice, and none of the other predators/scavengers have such a low tolerance of acetaminophen, that it would do them any harm if they ate the mice.
the only other reptile which might come into contact with the mice are Varanus indicus, I have no idea what their tolerance of paracetamol is? the rest are small lizards/geckos/skinks
At least they have found something which is relevantly harmless to most of the animals on the island, delivered in a way which is not going cause it to leach into the environment in such a way that would cause significant problems. But I really hope that
V indicus is safe from it, and that they have checked if that is the case!
The snake is responsible for the suspected extinction of at least 5 species of bird in Guam, and the decline and potential extinction of many others.
Extinctions and Loss of Species from Guam: Birds
that said, I dont think that this will actually deal with the problem in any significant way!