I think they meant, critical as in it was known this juror had a hard deadline for when their participation would no longer be possible. It wouldn't matter what the judge knew or didn't know about how close they were verdict wise if he knew that the juror didn't have long to go before they had to finish up.
I know people think the juror/s have been skylarking but I feel bad for all of them tbh, its a big ask to give up so much of your life for this for piddling compensation. I feel like jury trials just become less and less realistic as time goes on. The Internet, double income families, social media, people working longer before retirement etc, all mean fewer and fewer people able to serve especially on such long trials, fewer people who aren't already prejudiced, more chances of jurors doing their own research and adjacent risks etc. Its a medieval system that needs updating for the 21st century IMO