Mueller has assured Trump he is not the subject of his investigation. But, of course, even if he were, a constitutional impossibility, his performance of his office would not be affected. IOW, Booker is a dunce.
Watching them all come unhinged over the court pick is hilarious.
Step away from the Crack Pipe, Booker...
No, he hasn't. He told Trump he was not (at the moment) a "target". In this context, the word "target" has a highly specific and very narrow meaning.
Telling Trump he is not a "target" is highly misleading, so much so as to be an outright lie.
What Trump is, is a "subject" of a Grand Jury investigation (or more than one). I have BEEN a "subject" of a federal Grand Jury investigation, after very unwisely speaking to two FBI agents who showed up in my office one day without having a lawyer present.
A "subject" is one hair's breadth away from being a "target". The difference is, when you become a "target", the government has to notify you by sending you a "target letter" telling you that the prosecutor has probable cause to accuse you of a crime or crimes and that he will be presenting his evidence to a Grand Jury.
The easiest way to graduate from being a "subject" to being a "target" is to provide evidence to the prosecutor without first being given immunity. All the prosecutor has to do is to get you to make a statement under oath which conflicts with evidence he has (or has made up), and, bingo! You are now a "target".
In my case, I was collateral damage as part of a larger issue the government was pursuing, BUT, by giving evidence that the government needed without immunity, it would have been easy for the government to indict me to squeeze the people I worked for at the time.
As it turned out, I was granted "use immunity", testified, and the big fish threw a fundraiser for the Clinton campaign (Bill), and the whole thing went away.
President Trump is the subject, the only subject, of the Mueller investigation. As such, he can't get immunity (what would be the point - it's him they want) - and he's inches away from target status.
For a smart guy, he doesn't have a very good legal team. Pray for him, but keep your powder dry.