maybe he didn’t!!
1-no one got aisha’s birth certificate.
2-telling some she was able to pick up a baby does not tell if person was 12 0r 42?? thats how historians came up with figure.
3-as we know our prophet…its not likey.
4-muslims were the first one to recognize the need to marry girls over 18.
In fact first legislation was done in egypt.
Its very unlikely for respected reasonable man form muslim society to do so.