He points to the word قطنا qittana and makes the following claim:

First he claims that the word “qittana” is a word that isn’t understood ‘generally’ in Arabic. but is it the case? Let’s see.

Tafsir Al-Tabari

2. Tafsir Al-Qurtubi

3. Tafsir Ibn Kathir

From the above it’s clear that the word was infact understood generally and even used in poems.

He then claims Al-Qurtubi said that

I checked his tafsir and couldn’t find it so please provide citation.

Here you built your whole conclusion on a false premise, the word is Arabic and it was understood ‘generally’ as to mean a book [kitab كتاب] or destiny [Naseeb نصيب].

This doesn’t prove anything, there is alot of words used in the Qur’an only once.

I don’t know what the tafsirs differing has to do with the word being wrong or not Arabic, but let’s check how they differed ‘greatly’ using tafsir Al-Tabari.

The view of Al-Tabari

If we look at all the opinions we will find that they all revolve around either it being their books [The books in which their deeds are written] or their destiny [Naseeb نصيب]. also cutting the tafsirs and then saying they don’t make any sense in their context like how you did is distortion and deception.