"He "experienced" a narrowly selected group of peoples united by a common faith." = Fact
"He was, for most of his career in civil rights, dismissive of whites in the US who were not racist" = Fact
"he did not gain wide enough experience of 'whites from other countries' in his one brief journey to make any such generalization." = Fact
#1 is good
#2 is debatable because he did not trust whites to be honest therefore he thought all of them were inherently racist but I will let this one pass.
#3 Pure opinion. Who made you the authority on how much experience is necessary to change your opinion and come to a new conclusion?
How much experience is needed to say "hey all white people are not inherently evil" I would submit my opinion that meeting only one person is enough.