"Arabic writing at that time conveyed only consonants"
As I have shown, Arabic at the time had just letters, that could stand for consonants and vowels.
"..., which permitted a shift from a scriptio defectiva to a scriptio plena."
Although Rezvan does not say it explicitly ‒ nor does he state the contrary ‒, he gives the impression that the early manuscripts had no diactrics, nor vowel signs. But ALL early manuscripts has SOME diacritics and vowel (and hamza) signs.
"al-Ḥajjāj [introduced] a system to designate long and short vowels"
Since we still do not have ONE system to designate ALL long and ALL short vowels, I'd like to read more about the system of the 8th century.
"In practice only two of the systems noted by Ibn Mujāhid became widespread: the Kūfan, Ḥafṣ (d. 246⁄860) ʿan ʿĀṣim (d. 127⁄744), and, to a lesser degree, the Medinan, Warsh (d. 197⁄812) ʿan Nafiʿ (d. 169⁄785)."
just wrong. That TODAY only four systems are widely used ‒ of which he mentioned only two ‒ does NOT mean AT ALL, that at Ibn Mujāhid (245-324⁄859-935)'s time or in the following centuries 12 of his 14 riwāyāt were hardly used. The opposite is true: more than his fourteen were used.
"It is possible that [the St.Petersburg/Kazan] edition played a decisive role in the centuries-long process of standardizing qurʾānic orthography."
The final stage of the work on the unification of the qurʾānic text is connected with the appearance in Cairo in 1342⁄ 1923-4 of a new edition of the text"
nonsense
it was "Drawn up by a special panel of Muslim scholars"
nonsense, it was ONE man, Egypt's main recitor of the qurʾān (šayḫ al-maqāriʾ al-miṣrīya)
"today accepted throughout the Muslim world"
just wrong.
"in Zaydī Yemen, traditions remain which go back to a different transmitter of the text, Warsh."
it seems that Yamanī Zaydīs read Qālūn
The last two paragraphes are gibberish.
