Being someone formerly from the Police NSF. I would caution that notion carrying something along as a defensive weapon. Although yes you bring your tripod along as part of your shoot that is fine but don't bring something else that might in the end be mistaken as you carrying a defensive item to cause others hurt. As I said...it is a sad situation but let's not get over paranoid and start over imagining things.
Another things to note about using or bring something along to protect yourself as I would advice folk when I was doing police duties... IF YOU ARE NOT GOOD at using the item as a defensive weapon to protect yourself, you might end up providing the offensive individual(s) an item to use on you if they managed to snatch it from you. Remember if someone dares to attack you, they are most likely better fighter then you if not they will not pick on you.
I have seen people who got into that situation and got beaten with their own defensive item and also if it was just a bare handed fight...it can quickly become one where an item is used as a weapon. If you are not someone with the skill to defend yourself ( and those with you) well....then run and avoid a fight.
I hate to make light of what happen to the TS but this is a very rare but unfortunate situation. Don't let the knee jerk reaction cause anyone to go on a witch hunt and take matters into their own hands. Most of you here are rationale enough to balance things, we don't want someone here to misread this and overact and attack someone and found out they got the wrong person or over-reacted. Be careful in life( not just while you shoot) but let's send out the right message here.