Only if you're an idiot.
For big cases both the prosecution and defense do deep dive investigations into Juror's. At which point if they find out a juror omitted a potential bias they will bring it to the judge and request the juror be removed.
At which point the Juror who omitted the things can get in big trouble.
In normal times, and with normal cases, I'd completely agree, and I do agree with the point you make regarding juror background checks that are done by the court.
However, we are looking at a case which is probably going to be highly politicized, and a suggestion by a member that not doing everything possible to sit on a jury for a case like this is a 'duty' to pursue because of political issues.
The man he is criticizing decided to be upfront about his own potential biases, which is the right thing to do in jury selection. The only implication I could take away from the way the post was worded and the context was that the poster thought the man should have not said anything and potentially sat the jury, even if his 'bias' might cause issues later, in the eyes of the media, politicians, or the defense/prosecution teams.
As well, the point
@prinCZess made about the Damocles Sword hanging over any jurors and their families, due to the likely actions of the mass media, is still valid.
The constitution is already not standing.
Several states violated it in the last election, and no one is facing any consequences.
It's just a sheet of paper at this point.
We'll see.
I can admit we may reach a point the Constitution may become moot, however I do not think we have reach that point yet.
Particularly when it comes to the criminal justice system; when/if we have truly lost that, then we are in a post-Constitutional US.
I do not think we have lost it yet, and this case will be a good barometer of where we actually stand.