There are really only three reasons to insist — as so many do — that Aisha was only 9 years old when Muhammad, the Prophet of Islam (PBUH) married her: Either you are such a crazy Islamophile that you are willing to go to your grave insisting Muhammad could do whatever he wanted, or you are such a crazy Islamophobe that you want to insist he did, or you are such a weirdly religious sex-crazed pervert that you hope accusing him makes it OK for you to do it too.
There is absolutely no other reason to either make or repeat that disgusting claim. Aisha was married in 622 C.E., and although her exact birthday is unknown, Abu Ja’far Muhammad ibn Jarir al-Tabari recorded that it happened before Islam was revealed in 610. The earliest surviving biography of Muhammad, Abu Muhammad ‘Abd al-Malik bin Hisham’s recension of Ibn Ishaq’s Sirat Rasul Allah — The Life of the Messenger of God records that Aisha accepted Islam shortly after it was revealed — 12 years before her marriage — and there is no way she could have done so as an infant or toddler.
Furthermore, it is a matter of incontrovertible historical record that Aisha was involved in the Battles of Badr in 624 and Uhud in 625, in neither of which was anyone under the age of 15 allowed.
Finally, Imam Wali-ud-Din Muhammad ibn Abdullah Al-Khatib, dead for more than 700 years, recorded in the biographical section of Miskat al-Masabih that Asma, her elder sister of 10 years, died at the age of 100, 72 years after Aisha’s wedding. This makes Aisha’s age at the time of her marriage at least 14, and at the time of her marriage’s consummation almost 20.