> What's the reason for allowing judges to remove jurors who admit their intent to acquit a guilty defendant?
Arguably, the same reason judges should be allowed to remove jurors who admit their intent to convict an innocent defendant: jurors must apply the law impartially. The LII has a pretty decent primer on all this entails[1].
And almost all state laws require a jury to unanimously vote to convict, so empaneling a jury that has someone who will always acquit means that the jury's decision has been set from the beginning.
Personally, I live in a state that requires a unanimous vote to convict or acquit, and prohibits the judge from "poking at" a deadlocked jury[2]. In the few times I've been selected for a jury I haven't gone far enough to be asked if I would be impartial, and I'm glad because I've yet to decide where my personal ethics take me.
I'm of two minds of this. On one hand I do agree with you that it has the potential to be an important safety valve (not least because I think the US prison system is immoral and unjust...). On the other hand, historically it has a history of severe abuse, e.g. to let people go free for lynchings and the like.
The right to bear arms has a history of severe abuse as well, but I'm not one to throw the baby out with the bathwater. A jury that acquits a white murderer, then convicts a black murderer of the same caliber, is the textbook definition of an impartial jury (which is unconstitutional).
If they can't convince other jurors, no "harm" done. If they can, then perhaps the law is overkill. The judge seems to be overpowered here.