Even if this were true, it should not be a once a year event as these same people, have assembled and lived in harmony in the West (primarily Western Europe and US) for decades, but unable to do so in Islamic countries. You may already know that this is also a money making event for Saudi Arabia and Muslims from prosperous western democracies often are forced to book overpriced hotel rooms owned by the {un}Royal family to gain a Saudi visa.
Muslims gathering at Hajj has more to do with the universal message of Islam where people from different lands, colours, strengths, cultures, languages, rich or poor assemble.
So much for unity…..