That's not how that works lol. You are called to testify, you are legally required to do it or face jail. You answer questions truthfully. It's not a set up, it's what happens to ANYONE who committed, helped commit, witnessed, or otherwise, a crime.
Same thing happened with Mueller and all the claims of a "perjury trap." It isn't a trap when the prosecutor asks someone under oath if they committed a crime related to the current trial. It's literally upholding the law.
If the only options a defendant has, are to say they committed a crime under oath, or lie, then they did commit a crime.
They still have the option to remain silent. Though this can lead to an adverse inference being drawn. Another option is like what Bill Cosby did and try to work with the prosecutor to secure some measure of immunity from criminal proceedings that could stem from your testimony in a civil trial. Personally I don't think Cosby should have been granted any of that and just forced to face the fucking music, but rapists gonna rape I guess.
I don't know anything about the legal details - besides what I've read on the internet, aka RESEARCH - but I unfortunately watched the clip of Junior getting interviewed about his knowledge of GAAP and, in my opinion, the prosecutor laughed and played along with his "jokes" and he of course loved the positive attention and let his guard down. To some degree that seemed like a pretty good "set-up", but just like everything else, in a totally legal and normal to court proceedings way.
It's pretty easy for experienced interrogators to play someone who is overconfident and fairly dumb. It's interesting how Truump Sr. acts in these situations, though... he drops the BS and is very careful. Probably why he was worried about his sons testifying.
If you suspect a witness of being an accessory to a crime, then of course a competent prosecutor would "set up" that witness to jeopardize themselves. Admitting to a crime isn't a defense against prosecution.
"Donald Trump Jr. would have had the option of taking the Fifth Amendment," he said. "This is a civil case, but he still could say, I refuse to testify because my testimony could be used against me. He's decided not to do that, and so now as a result, everything that he's testifying to is fair game for prosecutors to consider. Prosecutors have looked at this case. They have chosen not to charge it as a criminal case thus far, but that could change based on Donald Trump Jr.'s testimony, so there's an inherent risk in taking the stand here."
That's generally how it works. Like when police ask much more minor criminals (or innocent people) leading questions to get them to say incriminating things.
remember how he committed a crime years ago when he was named in the mueller report but wasn't convicted because he was "too dumb to know he committed a crime" aka he was rich, male, and white?
According to the article, the stuff he said he let the accountants handle is stuff a competent criminal would've pleaded the fifth to, because he was still VP, and still responsible for what he signed as VP, and now since he's under oath, that testimony is evidence in a criminal case against him.
In other words, he admitted to being responsible and just not looking at anything