J.G.I

Just a side note, DCF has been suspended in Egypt until further notice. You'll have to come here, get married, go back to the US and file from there.
I'm Egyptian and my wife is American. We have been married for almost 4 years. We are living in Egypt and we had to deal with the embassy a lot. Since before our wedding(during which we had to battle them vigorously) till the birth of our baby girl, we've been to the embassy several times and we saw different couples trying to get married. In addition to that, we have been known to embassy staff during the revolution when the embassy closed down and we had to get a passport for our newborn baby girl. During that time, a CO at the embassy said that the most common profile they have for marriage cases is a younger man meeting an older woman online. So let me assure you that age does matter. From what I read about your situation, it perfectly fits their profile. You met online, you don't know each other very well(3 short visits don't count) and the age difference.
As an Egyptian, I totally understand why the CO said what he said to your fiance. It's almost unheard of to have a man of any age who hasn't been married before to marry a woman who won't give him children and assume that his parents are OK with it. However, I take your word that your fiance is a good man. Having that said, let me tell you what is the stereo type of a situation like that in the context of my culture. A younger man going after an older woman would end up having another wife at a later stage in life and have the children he wants and the laws allow that here in Egypt. He would get his parents blessings by telling them that(Not all parents would go along with that but few would). The cultural pressure in that regard is so huge, you cannot and you should not discard it. I believe the CO had that in mind except the part of having another wife since the laws don't allow it in the US.