Is it a joke?

„Dear me“ said the lady to the superintendent of the insane asylum,
„what a vicious look that woman has we passed just now in the corridor.
Is she dangerous?“
„Yes at times,“ replied the superintendent evasively.
„But why do you allow her such a freedom?“
„Can´t help it“.
„But isn´t she an inmate and under your control?“
„No, she is neither under my control, nor an inmate. She´s my wife.“