No, it wasn't.

Sadly, a good defence team could easily dispute a child's diary if that is the sole piece of evidence. Of course, if it was supported by additional factors it is likely that the diary would have been damning.

And to clarify and make sure this is 100% clear. I am not defending Chavis or anyone like him.

That is simply the only explanation - from a legal standpoint - that I can think of as to why he wasn't convicted for Alex's abuse.