Because the USA is so deeply involved with Wuhan, this particular experiment, and all of them for that matter.

To publicly condemn China is to condemn itself. Plus we wouldn't want the sheep to become outraged about these biological warfare labs and foolish and uncontrolled experimentation would we?

Russia isn't going to say anything even though they clearly know what is up - they have dozens of these things themselves they don't want to draw any attention to. It is bad for business so they keep their mouths shut.