Sorry to hear about your coworker I hope she recovers 100%

As for putting the dog down... About 99.9% of dogs are born followers, they don't like to be in the leader role. In a pack there is an alpha male and alpha female. They control the entire pack through body language and touch. When humans get a puppy they think it is so cute when it jumps up, steals our stuff, invites themselves on the the bed/couch/(insert other items here). We encourage them to jump up so we can pet them and generally let them have their way. This all feeds into allowing the dog to become the pack leader. Dogs NEED someone to be the leader and if the human does not step up to that role (intentionally or not) the dog will be forced into that position. Do they want to be the leader, no, but because someone has to do it they take it upon themselves to be the leader. Now add a few years to this dog in this unstable frame of mind, allowed to be dominant and alpha because the human won't take that position and you have a dog that is starting to show possesive and aggressive tendancies. You now have a dog that guards his space will growl or bite when asked to do something and whole other list of unwanted behaviors. Once a dog has had to be the leader for awhile (some dogs it is less time than others) it becomes harder for them to give up that position (depending on the dog). Some dogs are more than willing to have a human assume that role immediately whereas the next dog puts up some fight. Lack of exercise is a huge factor in dog behavior - being in a kennel is restricting the exercise therefor the dog has pent up energy contributing even more to the aggression. Dogs that are unaltered and not allowed to breed twice a year also have the sexual frustration which contributes to the aggression. Now put this into a breed that is already known to be a dominant breed and you have a recipe for disaster... Is it the dog's fault he bit someone- not a chance, is it the kennel staff's fault - partially because they probably didn't catch or ignored the subtle warning signs that an attack was imminent, is it the owner's fault - absolutely, it is their responsibility to keep the dog in a balanced, stable frame of mind.
Now hear me out on why I believe the kennel staff are at fault. Every dog no matter what they background of aggressive behaviour will give you warning signs that they will attack. Its the little things like their ear set, how the head is held, eye contact, the moment they freeze are all precursors to an attack. Now many dogs you can get away with ignoring these slight signs and you will never have a problem because they are satisfied that you will finish whatever you are doing and they are happy to submit to that but the dogs that have dominant tendency go through a though process much different. It is more like - the ears set changes, no response from human, the head becomes dominant, no response from human, the stare down begins and the human looks away solidifying the dogs mind that they are in control and it progresses from there. Many kennel staff don't have the necessary tools to deal with dominant dogs just because of lack of training. Being a dog lover and being the dog leader are two totally different things.
Back to the owner - it is his/her responsibility to bring to the kennel a balanced dog so he/she needs to find a trainer that can help them deal with the dog
I don't believe that the dog is aggressive. The attack was more likely a product of circumstance. Should the dog be put down? I don't think that should be the first thing to happen. This dog can be rehabilitated into a balanced member of society if the person knows how to do/go about it. If no one is willing to take that job on then yes put the dog down. It is sad when humans produce a dog like this and aren't willing to right the wrongs they have done and it is the animal that loses their life.