Why would community bot reject a suggested formatting edit that should have been approved ?
In this particular case, user Adam's suggested edit was most certainly valid, since we encourage code formatting in posts. However, according to the post revision history, the following sequence of events ensued (some guess-work):
Underlying here is the fact that a suggested edit isn't immediately incorporated once approved by someone reviewing the queue entry. Instead, (at least) two votes are required. See How do suggested edits work?