You seem to be saying that the fact that there are virus particles grown in a 2% medium contradicts the foundations of virology.
That's not "sterile." They're adding virus to cells that have already been grown. There's no reason why viruses *shouldn't* or couldn't replicate under these conditions.
And even if what you say is true, how does that undercut the foundations of Virology? What fundamental claims of the subject are incorrect as a result?