Only if those folks went to breeders that specifically bred proven protection dogs and got a dog that wouldn't or couldn't do the job.
Most 'oversize' German Shepherds come from breeders who don't compete or test their breeding stock in any way for example. In fact a lot of them seem to breed for easy going, laid back dogs.
So, I wouldn't call it bad genetics in this case I would just say the owners didn't do their research.....
The 'good' genetics are out there for those willing to put in the time and effort to research and put in the necessary training.
Smitty (rescue) Ilda WGSL 4/28/10 Autumn Australian Shepherd 10/9/11