Alright, I’ll give it to you in a formal, structured way.

Premise 1: Based on what we know about human nature in general, if a man old enough to be a girl’s father or grandfather had access to her while she was still a child, this would almost certainly not pass without leaving negative effects on her, in the long run if not in the short term.

Premise 2: Human nature is generally the same for us and for Muhammad’s people.

Conclusion: A marriage between a girl Aisha’s age and a man Muhammad’s age would be harmful even in Muhammad’s time.

You’d have to be stubborn to dispute Premise 1 or Premise 2.