She was mature at the time of consummation and married with consent so why do think it's wrong? Women in hotter climates attain puberty earlier.
WTF is wrong with you? How can a 9-year old kid attain "maturity" to engage in sexual relationships? I expected you to counter his argument by saying that there is no evidence to prove that she was 9-year old at the time of marriage. Disappointing.
I suggest you read Aisha's journals and narrations. She always praised and followed Prophet's teachings throughout her life till she died at the age of 64.
If she never mentioned a single issue with her marriage throughout her life and was most happily married then I don't see what's the problem with you.