There is certainly a bit of an idealogical contradiction with abortion and fetal homicide laws, (IMHO) but I honestly don't believe this applies to the Peterson case at all.
In the U.S. a woman's right to choose is predicated upon the 1973 Supreme Court decision Roe vs. Wade. (More specifically, the central holding of Roe vs. Wade as modified by Planned Parenthood vs. Casey.)
Although Roe vs. Wade affirmed that the word "person" as it is used in the 14th ammendment did not apply to the unborn, it would be a mistake to assume that this catagorically reduces the status of the fetus to that of a body part that may be removed by elective surgery at the whim of the patient. (For those who don't know, the 14th ammendment, (for purposes of this discussion) defines citizens of the U.S.)
The state has a vested interest in both preserving the heath of a pregnant woman and in protecting fetal life. Under Roe vs. Wade, the state's interest in maternal health becomes compelling at three months while the state's interest in fetal life only becomes compelling at "viability"--six months under Roe vs. Wade. (Under Planned Parenthood vs. Casey the viability line will be allowed to "float.")
What this meant in practical terms is the state may not regulate abortion at all during the first trimester and the state may regulate abortion during the second three months only in cases where protection of the woman's health is an issue. However the state may regulate or ban abortion entirely to protect fetal life post viability ---during the third trimester. Therefore while a third trimester fetus may be viewed as a "non-person" in the sense that it cannot be viewed as a citizen of the U.S., with all the rights and protections thereof, it is certainly not a "non-entity" in the sense that it is not alive and not human.
I think this is the key to Chappy's original question. "Non person" does not mean "Non human."
Forty states and the District of Columbia currently have laws banning most post-viability abortions. This includes California, the state where the crime took place. Laci's child was third trimester and the state therefore had and has a compelling interest in protecting such life without contradiction.