Of course, this doesn't invalidate his story of what went on in the meeting. This doesn't prove collusion, but expect the liberals to say that this person in the meeting was surely plotting the hacking of DNC and Podesta emails with Don Jr.
It would be a blessing if Mueller charges someone for collusion, under the assumption that they played a role in “hacking” the DNC server. Trump’s team would subpoena the server as evidence. If they destroy it or prevent it from being examined, Mueller won’t be able to charge anyone. All defendants get access to evidence in a criminal trial. In short, he can never try someone without revealing that it was never hacked by the Russians.
It isn’t illegal to have a meeting with foreigners who claim to have information validating Hillary’s ties to Russia.
Isn’t that what the other side is seeking about Trump?