Shafiq al-Hout in his book My Life in the PLO says in relation to Arafat's first speech at the UN:
He also asked Mahmoud Darwish and me to include all the vowel marks in the text clearly in bright red ink. We did so, but despite our best efforts, he still managed to ride roughshod over the complexities of Arabic grammar as he read out the speech.
What was the nature of Arafat's difficulties with Arabic? My guess is that he simply had poor command of Modern Standard Arabic, used for international communication, even if he fluently spoke a local dialect (he was born and raised in Egypt.) Is this correct, or were there other linguistic particularities? (E.g., king Abdullah II of Jordan is known to speak imperfect Arabic, due to his essentially British upbringing.)
Remark One could google up the records of the speech, e.g., this one. Perhaps these could help to settle the debate about grammar vs. pronunciation. IMHO, if Arafat was unsure about the sound of MSA, this probably was also the case with the grammar. On the other hand, al-Hout, clearly speaks somewhat in jest - another key addition to the speech, according to him, was asking Arafat to shave.