The more that is coming out about this, the less I think it's actually a problem for JW's as such.
This individual sounds like your common-or-garden unstable personality, of the sort we hear about all the time in all kind of places.
Disfellowshipping (or other removal/rejection from a religious community), firing from their job or being rejected in love, there are a lot of people like this (overwhelmingly men, sadly) who react violently, as we are seeing on the news these days - attacking their former employer, former school/college, ex-partner or whatever.
Only the most vehement enemies of JWs - the sort who will use any negative story like this to attack them - are likely to get mileage from this story, unless something very different emerges.
However, how the Org or individual Witnesses themselves choose to react to this single incident will be interesting. Will they overreact/go overboard on security, or just recognise (as according to their understanding of the Bible) that this is just part of the 'times' we are living in?