Why not? Should they stand on this alleged principle while babies die?
In fact, the existing laws are null since they contradict the natural law. The judges not only can, but must nullify these laws.
No. The judges should judge the laws. That's what we hire judges to do.
1. The legislatures are the proper place for such laws to be nullified. In case you'd missed it, the legislatures have been doing their parts by passing laws to limit abortions. The USSC strikes them down, based on the whim of the judges.
2. If we decide that "whim of judge" is the proper standard of law, as you are suggesting, then this standard will be (and is) followed in general. Which explains why we get judges making all sorts of bad laws by judicial fiat -- including the legalization of abortion.