Mohamed had sex with his wife, A wife who was young. But to be fair the childs parents sold there daughter to him. there were no laws broken so just stop. Mohamed was in his legal rights you can not impose your morals to the past.
Having sex with his wife does not make her not a child. Plus you have not provided any proof that they sold it to him. The only thing we know is that Mohammad pushed for it after seeing the 6 year old girl in a dream. And we can impose our morals in the past if the immoral act was so horrible that they deserve to be vilified.