He was crying as he was ending Shahnameh with that Arab invasion wound. Don't blame him. To be fair, some researchers suspect that this part and some other parts were added to Shahnameh by others, and it wasn't Ferdowsi's words as we know that he ended it while describing Omar Bin Al Khattab as Ameer Al Moumeneen. He was born a Sunni Muslim, like Hafez and Saadi. Though, he was quite a nationalist as you know so it wouldn't be strange for him to repeat some racial slurs any way.
Not to every single incident, but it shows what the relation was like back then and what it is like today. No big difference still, so it is fair to assume that Persians can do such acts deliberately because we have never quit our mutual animosity.
It doesn't mean it directly, but it increases the likelihood as the mentality on both sides haven't changed much. The same racial slurs are being used on daily basis in Persia. They are being used here in PDF. Just check the recent posts of
@scythian500 and many others. Please also note that this poem was written when most Persians were Sunnis. So now we have got a sectarian side to the matter that didn't quite exist back then.
I also think that religious hatred between two members of two sects is stronger than the hatred between the members of two different religions. And you are always into denial and defense to save Iran's public image (which is already not great and widely exposed). You have got to tell the truth as it is for things to improve. Hiding your dirty laundry under the rug won't help much.
