I've sat through this stuff before Kappy. Just because we don't get all the questions you can see what happened. To disqualify a juror you need a reason. The fact they showed him something he wrote, asked if that was him, and he said yes shows before that they asked him that question.
Kappy I work as a paralegal and know what i am talking about here.
The lawyer probably asked him something like have you made statements to anyone, or on social media. Then after he answered no the lawyers showed the judge the statements, then showed him the statements and asked if he wrote them. He was caught, said yes and was excused.
You wouldn't show him those statements until you ask him. It wouldn't be a story unless he had lied trying to get on the jury. It's a very reasonable assumption.
Neither side wants a person like that on a jury.