The problem with that hypothesis is, a weaponized virus would have a much harder bite and a much more rapid onset than this one. A good biological agent is both quickly debilitating, and self-limiting. This one is neither.
The rest of the story has not been told or seen yet. I would not close this case so hastily and draw this conclusion. Give it some time...it may surprise especially if this virus can behave as a HIV type virus....that can hide for a time....then reappear, or mutate many, many times to survive.
APAK