Rape of an adult woman

Volokh, in a post about a murder case in Louisiana, says --

... precluded by Coker v. Georgia -- which held that the death penalty for rape was unconstitutional, and which many have read as generally foreclosing the death penalty for crimes short of murder (but which the Lousiana Supreme Court has interpreted, controversially, as allowing the death penalty for rape of children)?

I don't see the controversy, the opinion in Coker v. Georgia includes this paragraph --

These recent events evidencing the attitude of state legislatures and sentencing juries do not wholly determine this controversy, for the Constitution contemplates that in the end our own judgment will be brought to bear on the question of the acceptability of the death penalty under the Eighth Amendment. Nevertheless, the legislative rejection of capital punishment for rape strongly confirms our own judgment, which is that death is indeed a disproportionate penalty for the crime of raping an adult woman.

It seems pretty obvious that the court was at best leaving open the question of the death penalty for the rape of a child.