"The fact that a Sylvia Plath may die young does not necessarily mean an Introduction to Poetry class should carry a warning that poems may be hazardous to one's health, " he said.

All of the self-discipline and all of the self-denial in the world can do nothing -- this seems to be one of the implications of this poem - can do nothing to protect the poet from an untimely death.

It's about the untimely death of a poet.