Not as diabolical as you make it sound. They use it to calm the person before the death drug is given. Read this info on it from Mayo Clinic:

"Midazolam injection is used to produce sleepiness or drowsiness and relieve anxiety before surgery or certain procedures. When midazolam is used before surgery, the patient will not remember some of the details about the procedure. Midazolam injection is also used as an anesthesia to produce loss of consciousness before and during surgery.

Midazolam injection is also used to treat status epilepticus, a severe type of seizure where there is more than one seizure within 5 minutes.

Midazolam is a benzodiazepine. Benzodiazepines belong to the group of medicines called central nervous system (CNS) depressants, which are medicines that slow down the nervous system.

Francis has been so duplicitous since the second he stood on the balcony it's impossible to know if he's really suffering or just play-acting, so it's hard to sympathize with him. With the vastly increase speed of his dismantling of the Church recently, I suspect he's handed over power to someone else (or some group) that does all the work while he naps so he can stay mostly awake at his next PR appearance.