I wouldn't call it odd if they were deliberately trying to get caught or martyr themselves in a hail of Police bullets, which seemed to be what they were trying to do. They were there to make a point and by simply killing him and running, it might have been days before England realized the true reason behind the murder. But by standing around and speaking to passers by and allowing themselves to be filmed, within 24hrs the world has been exposed to this murder as well as the reason. They have received maximum coverage which was their main goal and all they had to do was kill one person in the most horrific way possible - maximum result for minimum effort - sometimes this is worse than a killing spree.
I still stand by my choice that its a terrorism related matter simply because the sole purpose of the murder was to install fear and intimidation within community. Had they only been interested in murder and not interested in the public's reaction to it then yes I would have agreed that it was nothing more than murder
And yes you're totally right that it shouldn't matter whether or not he was a soldier but the fact remains that when its reported that a murder has occurred outside military barracks, the first question that will be raised is if military personnel involved.
