...the quote that I gave from Muhammad Asad,
a former Jew himself, who pointed out that, as mentioned in At-Tabari's tafsir, some Jews came to the Prophet Muhammad pbuh and said, "How can we follow you when you do not believe Uzayr is the son of God?".
Notice that the Qur'an doesn't say that the Jews believe Uzayr is the son of God, but the Qur'an is very precise in saying that the Jews say Uzayr is the son of God. Thus, it cannot be a contradiction in any way since the Qur'an is only responding to the verbal proclamation of a group of Jews!
Also interesting is Dr. Muhammad Mohar Ali's comments on this issue:
Of course there is no evidence in the extant Old Testament about it; but the Qur'an was not referring to what is written in the Old Testament about 'Uzayr but to the belief and assertion of some of the Jews of the time who regarded 'Uzayr as the son of God. In fact the 'ayah in question, 9:30, starts with the expression: "And the Jews say". The commentator Al-Baydawi, to whome Watt refers a number of times in his book, (fn. Watt, Muhammad's Mecca, 108, note 2 to Chapter 1 and notes 2 and 10 to Chapter III) makes it clear with reference to this 'ayah that because the Old Testament was given its present form by 'Uzayr, many of the Jews of the time considered him a "son of God" and that specifically at Madina there was a group of Jews who held that belief. Al-Baydawi futher points out that the 'ayah in question was read out and recited as usual but no Madinan Jew came forward with a contradiction (fn.Al-Baydawi, Tafsir, I, second Egyptian impression, 1968, p. 412). It is to be noted that this 'ayah is unanimously regarded as Madinan. Hence the silence of the Jews of the place on the matter is suggestive enough, particularly as they were avowed critics of the Prophet.
Not only Al-Baydawi but also other commentators mention that the 'ayah refers to the views of a particular group of the Jews. For instance, Al-Tabari bives a number of reports together with their chains of narrators specifically mentioning the leading Jews of Madina who considered Uzayr a son of God. The most prominent of those Jews were Finhas, Sullam ibn Mishkam, Nu'man ibn Awfa, Sha's ibn Qays and Malik ibn al-Sayf (fn. Al-Tabari, Tafsir, XIV, 201-204). Similarly, Al-Qurtubi mentions the same fact and the same names adding that the expression "the Jews" occuring at the beginning of the 'ayah means "some particular Jews", just as the expression "people told them" (qala lahum al-nas) means not all the people of the world but some particular people. He further says that the Jewish sect who held that 'Uzayr was God's son had become extinct by his (Al-Qurtubi's) time (fn. Al-Qurtubi, Tafsir, Pt. VIII, 116-117). (Muhammad Mohar Ali, The Qur'an and the Orientalists, Jam'iyat 'Ihyaa' Minhaaj Al-Sunnah 2004, p. 66)
So as for what he quotes,
Notice the words "proposed" and "assumption". There are no records from any Jewish community that believed Ezra was the Son of God!
First of all, this is the fallacy of
argumentum ad ignorantium which we can refute with the expression, "absence of proof is not proof of absence". In other words, just because we don't have Judaic records that shows that Jews believed this, does not prove that no Jews ever believed this!
Secondly, as was previously mentioned, there are specific historical narrations related by Qur'anic commentators like Al-Baydawi and At-Tabari which state the names of specific Jewish leaders who came forward to the Muslims and said "We cannot believe you since you do not accept Uzayr as the son of God". And notice that the Qur'an doesn't say that the Jews
believed Uzayr was the son of God, it says quite clearly that they
said he was the son of God. So, the Qur'an was responding to an explicit proclamation of the Jews. Either the Jews were intentionally lying, or they actually believed what they said - but in any event the Qur'an can't be wrong since the Jews of Madinah actually
said this.