Actually what caught their attention isn't all that important since it had to be rewritten using a fabricated decoder. Are you saying had he included a sentence saying that emails about ordering pizza had caught their attention? Yea, I guess it would have been a nice detail to add in order to give the whole pizzagate name context but I don't see any issue with not including it either.
The story isn't really in what those emails said it's what was fabricated after.