There's no real proof that this is a weapon.
What is the definition of or some examples of a "bio weapon grade infection" anyway?
I'm not convinced that man has or can yet make a virus more deadly and contagious than nature can.
Either way, time will tell.
We have had bio weapons for at least half a century now. The tech to modify viruses is pretty well documented I think.
Bio weapons, yes but that doesn't mean viruses necessarily. To be sure, research has been done but rational actors long ago came to the conclusion that a virus as a weapon is pretty stupid as you have no way to contain it, at least not if it is very effective. Bacteria based weapons are more likely but biological weapons in general aren't very good in terms of achieving military goals or are at least less useful than more conventional weapons except as perhaps a weapon of terror.
In any case, what is the evidence that this particular virus is not natural? It seems to follow a line of similar viruses that have developed over the decades. Maybe they are all weapons but to what end? Even this one seems a very poor choice for a weapon. Many people likely have mild or no symptoms, potentially increasing its spread but wouldn't you want to be able to easily contain a weapon? It's also not nearly as deadly as other bio weapon choices would be. Or at least that's what the evidence suggests so far.