I know this is just one case, but to me the 9mm is not a proven performer.
The 9mm is the most used round buy police and military world wide. It was used by the british and Germans in WW2. It was used by the british SAS to good effect in terrorist and hostage situations. It is the most tried and tested hand gun ammunition ever produced.
And you think its not a proven performer.
The person could have being hit by the same number of rounds in the same place with .40 or .45 and and had the same result. Hit someone with 9mm .40 or .45 in a vital area they will go down hit them anywhere else and will or won't depending on the person.