Except that if the account of the meeting is true- and I'm willing to accept that it is-  he did nothing of the sort. He did not meet with a representative of the Russian government. He wasn't offered help by the Russian government to influence the election, as far as we know. According to the account given, he wasn't even offered damaging information on Hillary Clinton. Instead, the person he met with wanted to talk about the US Magnitsky Act, which is entirely plausible in that she had close connections to Russian industrialists.

Whether all this is true or not, DT Jr. has the perfect alibi. He was being offered damaging information on Hillary Clinton. It could be that the information was of a personal nature; it could be that it was evidence of a crime; or it could be that it was evidence of a national security concern. So out of political, civic and patriotic duty, he took the meeting, only to find out it was just a come on.

Over to you.