I don't think so, but you know yourself better.
You seem like a nice person, FP. You invited this guy (a distant relo, not someone too close) to your sister's wedding. You let it go that he didn't show up....but were looking forward to a congratulatory call. You seem to know the rules of courtesy better than your distant cousin. And you seem to have better manners and you seem to have a better awareness between right and wrong. So....drop the cynicism for a few minutes.....and use your many positive qualities for the polite education of this fool cousin of yours :)
You are too kind. I am not really a nice guy and in fact I hate just about everyone except immediate relatives and keep everyone else at distant. His sudden refusal to attend did hurt my ego and pride (although I am not an arrogant man) but I feel that his actions also brought some amount of discomfort to my parents my young sister. She had meticulously prepared for every facet of the wedding detail, down to the last pregnant aunty. Although his absence did not create a havoc in the least bit, it did present my sister with some minute amount of distress. I treat my friends and even their friends with great care, courtesy, and compassion. And I except the same in return.
If he does not know the difference between right and wrong, cultural ethos, social and ethical responsibilities then how will he be able to carry out agreements of marriage?