Why was the word "أولياء" (awliyāʾ) not declined in verse 20 of Surah Hud, even though its hamza is not for feminization, knowing that nouns ending with an extended alif are not declined if the hamza is an additional one for feminization?

Ibn Malik mentioned in the Alfiyyah that the alif of femininity (alif al-ta'nith) absolutely prevents a word from being diptote (ghayr munsarif). Some commentators clarified that this includes the alif of femininity in indefinite and definite nouns, singular and plural forms, and in nouns and adjectives. They exemplified this with broken plurals (jam' taksir) on the pattern of "af'ilaa'", such as: asdiqa' (friends), anbiya' (prophets), and awliya' (saints/guardians), where the extended alif in them is extra and indicates femininity.