Look at my first post on page one of this thread. I complimented Shapiro and said I’ve always thought he was a sharp guy. I listen to his post cast and respect many of his ideas and arguments.
This interview was not one of his finer moments. It’s obvious and he knew it as evidenced by his apology
It was definitely not one of his finer moments and as you say he acknowledges it.
I maintain it was because he was caught off guard by Andrew Neil right from the very start (Neil attacking Shapiro very first thing with a tweet made years earlier about Palestinians).
You can say Shapiro should have handled the interview better, and in hindsight I'm sure he would agree.
But Neil, as others have pointed out, was contentious and combative, and in the future when Shapiro is out hawking his books he will have to develop a game plan for dealing with bad actors like Neil.