It's a vague term because they don't know what exactly happened yet and anomaly is a technical term that those in the industry know. Explosion has a technical

It's a vague term because they don't know what exactly happened yet and anomaly is a technical term that those in the industry know. Explosion has a technical meaning too, and many things that look like an explosion aren't. AMOS-6 for instance was not an explosion, even though it really looked like one to a bystander. This isn't excessive pedantry, it's jargon meant for an audience that will understand it and not take more away from a statement than they intend to say. Better to use the word that means "something bad happened" rather than a word which means something specific only to have to follow that up with "sorry, we were wrong, it wasn't that, it was..."