Just throwing this out there on the Bioweapon theory:
1. If it escaped unintentionally (which I think we can all agree is almost certainly the case) It might not be quite finished yet. Let's think of this as like an 80% solution on a weapon.
2. You guys are thinking in terms of military effectiveness, which is not where bioweapons shine, and not really how PRC doctrine runs. Something like this is more of a weapon for right before, or at the very beginning of a shooting war. Once hostilities break out a lot of travel between belligerents is already stopped. That is to say, no one is coming into China. SO they smuggle several hundred carriers in through Mexico (or through north Africa into Europe) with credit cards and instructions to take a nice long 3ish week vacation traveling all over America/the EU. Then the war starts. Can you imagine the West trying to swing into a wartime economy, and produce a bunch of weapons to fight the PLA, as well as replace the things we need in the States that aren't made there, all while no one can go to work because a 15-20% death rate flu is ripping around? How about the effectiveness of the extra soldiers that dropped off kids with grandma and grandpa to deploy, now that their kid's school bug killed grandma and grandpa?
Is it definitely a bioweapon? Maybe, maybe not, but it would be a good one, especially if this is the rough draft. Did it come from the Wuhan lab, either through accidental jump from a lab animal to a tech, or poorly disposed of lab animal remains? I would bet a fair amount on that.
One last thought: This is described all over as "fast mutating" so vaccines will be a long term challenge. Even if it wasn't a weapon originally, it probably is now.
