The insane and the mentally deficient: may the guardian divorce on his behalf?

It was in the book of Sayyiduna Abdullah bin Amr (may Allah be pleased with him) that when an insane man harms his wife, his guardian may divorce the woman on his behalf.

Ata (may Allah have mercy on him) said: The guardian of an insane person may give a divorce on his behalf, but he should wait in case he becomes well.

Sa'id bin al-Musayyib (may Allah have mercy on him) said: The divorce of one whose reason is overcome and who is mentally deficient (ma'tuh) is not valid; his guardian will give the divorce on his behalf.

Ayyub (may Allah have mercy on him) said: I wrote to Abu Qilabah (may Allah have mercy on him) asking about the wife of an insane man for whose recovery there is no hope: may his guardian divorce the woman on his behalf? He wrote back to me: He may not divorce her; Allah has put this woman to a trial, so she should be patient.

Al-Zuhri (may Allah have mercy on him) said: A divorce given by the guardian of an insane person (on his behalf) is not valid.