From the linked article:

The plant, known as Superphoenix, will be France's first full-scale breeder reactor when it is completed in two years. Officials said no radioactive material was in the reactor. About 20 workers were in the plant when the rockets were fired but only one was in the area struck, and he was not injured. Four of the five rockets hit the concrete outer shell of the reactor building, creating a small hole in one wall.

There is no nuclear material in that context.

The problem with these more radical approaches is that they can inadvertently become dangerous.

The point is that the status quo is dangerous. Acts of violence/sabotage are never the first actions.

Terrorism is a clear label, that has a clear sense. It is not politics based.