Is it obligatory to reconcile with unbelieving colleagues before Hajj if their boycott was due to zeal for religion and Arab identity after hearing something displeasing, and would Hajj be diminished in any way by not reconciling with them?

Allah has commanded Muslims to speak kindly to people, and this includes both Muslims and non-belligerent disbelievers. As for belligerent disbelievers, they should find harshness and severity from us. Allah has permitted kindness towards disbelievers who have not fought us or driven us from our homes. Showing kindness to them includes all forms of benevolence, except for anything that involves glorifying their religious rituals or showing them religious affection. Therefore, treating peaceful disbelieving colleagues well is something encouraged by Islamic law.