The host speaker announced, "There is a black man here, we can't have this , take him out"
This isn't altogether surprising. Saudi Arabia officially stopped slavery in 1962, after pressure from the international community. The Arabs had been buying sub-Saharan slaves well before whitey even set foot on the continent.
Just let that sink in ... officially stopped slavery in 1962. It may still go on unofficially.
Some Saudi citizens (c. 10%?) are Afro-Arab, i.e. they're of mixed heritage. A derogatory term for black people in Arabic is 'abd'. This means servant or slave (e.g. the name Abdullah means 'servant of Allah'). Abd is used as an insult in Sudan, I believe, towards Sudanese of dark complexion.