Firstly, if you actually look up the definition, it explicitly includes the phrase 'typically accompanied by armed troops or warships.' So.

Secondly, convoy can mean either. It can be civilians OR military. It's not a proper reflection of the news event, because a bunch of soldiers vs a group of civilians being massacred are totally different events. So even if you ignored the literal definition being soldiery, it's like calling a school shooting a 'building shooting'. Everyone knows that a double digit percent of people only read headlines, things like that should be explicit.