This is also valid. I have never served on a jury. But, I have served on committees that can get very heated. As a person who does not relish conflict, I "check out" and let the loudest person carry on.
Sounds like this juror is very much like that. He wanted out of the space with these people, so if he agreed, he could leave.
Introverts probably are not good for jury selection.
Jurors are not supposed to be advocates one way or another, if they are doing that they are engaged in misconduct. The evidence is supposed to speak for itself, either it is compelling or it is not. If it is not compelling then they are supposed to acquit. The fact that he talks about "pushing harder" means that he was a bad juror to start with and did not understand his function in the trial.
At the end of the day even if someone is acting inappropriately you still have a vote, so that is no excuse.