As HRS134 suggests, there's not enough information here for the online jury to decide if the case is being handled properly.  It's possible the woman was totally abusive and should get an additional charge of use of a deadly weapon.  On the other hand, maybe the man was about to do something bad to the baby, so she saved it by hitting him.

Wait for more information that might come out in a future report.  Or start your own investigative service, be the next Sherlock Holmes or Inspector Gadget.  Save the world!