Why Did Bill Gates Cancel His proposed Visit to Nigeria?

It is obvious that the United States of America is angry over the controversial pardon granted Alamieyeseigha, by President Goodluck Jonathan, last week. They are also angry that Nigeria summoned its envoy for questioning for daring to voice concerns over the pardon to corrupt persons. Yes Bill Gates plans to visit has been cancelled, but is Bill Gate also angry about how Nigeria handle corruptions? The billionaire said NO, but his reason for cancelling his planned visit is not clear.

Is Mr. President wrong? If he yes, how does it concern Americans and the billionaire. I thought President Jonathan was, President Obama's very good friend.