Part of his "proof" for the assertion was the fact that the Secret Service didn't try to stop the meeting. That is total horseshit for two reasons: candidate Trump's children and extended family were not under Secret Service protection when the meeting occurred and, even if they were, the Secret Service protective detail doesn't serve as on-the-spot lawyers for any of their charges because they're not even attorneys.
Many lawyers with extensive professional experience in both criminal law and election law have now been interviewed by the media and have laid out how Trump's son, son-in-law, and campaign manager may have violated a number of criminal laws and how they could be prosecuted by Special Counsel Robert Mueller, who is acting as a special prosecutor investigating the Trump Russia scandal.
New York Magazine published an excellent interview last week with attorney Robert Bauer (link here) who provides a detailed explanation of what crimes the Trump team trio may have committed and the penalties they may face. It's a bit oddly formatted but nonetheless fascinating reading, and I highly recommend it if you're interested in this subject.
This brings us to an interesting hypothetical about what might happen if Donald Trump Jr. and the President's son-in-law Jared Kushner are indicted, arrested, and facing a criminal trial.
Would the President continue to keep his indicted son-in-law on the White House staff? Would he preemptively pardon both his son and son-in-law, using the presidential pardon power, thus rendering any criminal prosecution as pointless, much like President Gerald Ford pardoned disgraced former President Richard Nixon to keep him from being put on trial?
Legally, he could do either or both of these things. From the standpoint of politics, however, both would likely be seen as monumental mistakes and cost Trump support in both his party leadership and among Republicans at large.
But Trump very well could do one or both of these things, because he seems impervious to constructive criticism and is also fiercely loyal to family.
If he should go down that road, it would likely paralyze his presidency, to a possibly greater degree than occurred during Nixon's final months in office, and doom Republicans' chances in the 2018 and 2020 elections.
In other words, let's hope we get to this point and that Trump chooses these self-defeating options. If we can't get him out of office and the 2016 election could never be done over, better a weak, powerless Trump than one flexing his power.