That's pretty standard islamic apologetics aimed at a western audience. It's all pretty modern and IIRC there's not much stuff that supports it and almost nobody accepts it in the muslim world.
Stuff like:
It is illogical to assert that Khawlah would have suggested a child as a companion for the Prophet, Aisha must have been of marriageable age.
Is just unsubstantiated.
More evidence is provided also by one of the earliest authors of Islam, Ibn Ishaq, who writes, that Aisha and her elder sister Asmaa were among the first 80 people in Mecca, who accepted the Prophets call to Islam. He adds as he mentions Aisha, that she was then a young girl. But how old can she have been then? Old enough to be mentioned among the people, who had taken an important step adopting a new religion. Maybe 10 or so?
A) A child of 6 can easily say that they accept a new religion if their parents make them.
B) Since the quran/hadith were written after Mohammed's life, of course she would be mentioned specifically, regardless of her age because she married him and was a prominent figure in the religion. The texts themselves are not objective contemporary observers, they are after the fact narratives, and narrative building will select out important figures even if they are just children.
We know, that the time between the first revelation of the Prophet and the migration to Medina (where the marriage to Aisha took place) were thirteen years. So we can say that even if Aisha was only a newborn baby when she became Muslim, she must have been at least fourteen years old at the time of her marriage. The Prophets daughter Fatimah (p.b.u.them) was born when he was 35 years old, meaning that at the time of the marriage to Aisha in Medina she would have been 17 or 18 years old.
A minute ago you were saying they weren't sure about how long a year was. Regardless, this opinion is contradicted in the Hadith and by Fateh-al-Bari's commentary:
Sahih Bukhari Volume 8, Book 73, Number 151 wrote:
Narrated 'Aisha:
I used to play with the dolls in the presence of the Prophet, and my girl friends also used to play with me. When Allah's Apostle used to enter (my dwelling place) they used to hide themselves, but the Prophet would call them to join and play with me.
Fateh-al-Bari page 143, Vol.13 wrote:The playing with the dolls and similar images is forbidden, but it was allowed for 'Aisha at that time, as she was a little girl, not yet reached the age of puberty.
The old Aisha proponents are a fairly modern phenomenon, which supports the idea they're a response to modern western horror regarding the child spouse idea.
There's also far more than one hadith that covers it:
Bukhari Volume 7, Book 62, Number 64-65:
"Narrated Aisha that the prophet wrote the marriage contract with her when she was six years old and he consummated his marriage when she was nine years old. Hisham said: "I have been informed that Aisha remained with the prophet for nine years (i.e. till his death)."
Narrated 'Aisha: that the Prophet married her when she was six years old and he consummated his marriage when she was nine years old. Hisham said: I have been informed that 'Aisha remained with the Prophet for nine years (i.e. till his death)." what you know of the Quran (by heart)' "
Volume 7, Book 62, Number 88:
"Narrated Urwa: "The prophet wrote the (marriage contract) with Aisha while she was six years old and consummated his marriage with her while she was nine years old and she remained with him for nine years (i.e. till his death).""
Bukhari vol. 5, Book 58, Number 234 says:
"Narrated Aisha: The prophet engaged me when I was a girl of six. We went to Medina and stayed at the home of Harith Kharzraj. Then I got ill and my hair fell down. Later on my hair grew (again) and my mother, Um Ruman, came to me while I was playing in a swing with some of my girl friends. She called me, and I went to her, not knowing what she wanted to do to me. She caught me by the hand and made me stand at the door of the house. I was breathless then, and when my breathing became all right, she took some water and rubbed my face and head with it. Then she took me into the house. There in the house I saw some Ansari women who said, "Best wishes and Allah's blessing and a good luck." Then she entrusted me to them and they prepared me (for the marriage). Unexpectedly Allah's messenger came to me in the forenoon and my mother handed me over to him, and at that time I was a girl of nine years of age."
Hadith of Sahih Muslim, Vol 2, Number 3309
Aisha reported: Allah’s Messenger married me when I was six years old, and I was admitted to his house at the age of nine….
Hadith of the Sunan of Abu Dawud, Vol. 2, Number 2116:
"Aisha said, "The Apostle of Allah married me when I was seven years old." (The narrator Sulaiman said: "Or six years."). "He had intercourse with me when I was 9 years old."
History of Tabari Volume 7, Page 7:
"....my marriage (to Muhammad) was consummated when I was nine....."
From Tabari, volume 9, page 131
"Then the men and women got up and left. The Messenger of God consummated his marriage with me in my house when I was nine years old. Neither a camel nor a sheep was slaughtered on behalf of me"......(The Prophet) married her three years before the Emigration, when she was seven years old and consummated the marriage when she was nine years old, after he had emigrated to Medina in Shawwal. She was eighteen years old when he died."
