I think it as because most people don't equate most other things with gun ownership.  Also It is a pretty common standard to pull the "they are coming for our guns next" to just about any law or politician one doesn't like.  Literally every President ever, someone has told me he will come for our guns, even Trump.

 I think in regards to State legislation this is one of those rare reverse processes.  Typically States enact their own laws on a subject, like marijuana, and then as more and more States jump on board the Federal Government then acts and creates an overall standard.  

 I used to have a chart of US laws that started with State legislatures and became Federal law, almost all of them right after 50% of States had laws that were similar.  I can't find it now.

 
Don’t understand the hoopla about RvW,
when a State making a decision.
about Guns, is perfectly OK,
but is not going to be,
when it is about Abortion?

 But a State can't completely outlaw guns right?  RvW isn't as protected as the 2nd in that regard.  


 As for the Human life/fetus/baby timelines there are consistent medical definitions for those questions but they don't address the ethics of abortion.  It's like defining cardiac arrest vs homicide versus intentional homicide.  

 I don't know what the timeline for "some" is.  

The medical terminology is consistent, as in exactly the same by definition, but not exactly applicable to the ethics discussion in regards to abortion.  

 Embryo = conception until the eighth week of development.

 Fetus = end of week 8 until birth.

 "Baby" is not exactly a medical term that is sectioned off by length of the human fetus in relation to it's removal from the birth canal.  A "baby" would be classified by either being alive or not alive and by term length.  

 Maybe the question is when is a human fetus considered to be "born" or "fully born" which typically is when the cord is cut but that is not an exact and required medical standard.  

 Perhaps a human fetus that is crowning is 3% born, halfway is 50% born and everything but the last toe is 99% born.  Using medical imagery like ultrasound prior to birth one could average the estimated mass of the fetus and assign a specific preliminary fetal volume.  At that point the measurement of percentage "born" by length or mass extracted from the birth canal would be calculated using that specific fetus' preliminary fetal volume.

 Once the fetus is 100% "born" or extracted from the birth canal and severed umbilically from the mother, it could then have it's post-birth physical mass measured for accuracy to the pre-birth volumetric model.

 The question then would remain, at what volumetric percentage should the term "fetus" be changed to "baby".  My suggestion is at .01% fetal mass exposure that is exterior of the birth canal.

 This same process could be applied to non-natural birth methods such as surgical removal.

"The American College of Pediatricians concurs with the body of scientific evidence that human life begins at conception - fertilization…."

 This addresses the term "life" and not the term "baby".  My understanding is that the question was:

"And if it is a ‘Baby’ only after birth,
when does it become a, ‘Baby’ ?"

 I would say after it is "born" or surgically extracted from the mother.  




"What does that have to do with;
" when a State making a decision.
about Guns, is perfectly OK,
but is not going to be,
when it is about Abortion? ""

 You posed the question about States and gun laws in relation to abortion.  When I ask "But a State can't completely outlaw guns right?" I am addressing specifically US States, and laws specific to guns.  When a State makes a decision about Guns I interpret it to mean laws about Guns.  That, to me, has something to do with your question asking about States making decisions about guns, and decisions about abortions.

 So a State can not make a law that forbids all forms of gun ownership.  Can they make a law that forbids all form of abortion?  As it stands now each State can make individual abortion laws, but can not completely abolish it, just like gun laws.

 What I see as unique to the latest abortion legislation is the imposing of one State's law onto another State.  These allowances to sue people that leave one State to go to another State seems excessive.  For instance if conceal carry is illegal in CO so I go to NV and conceal carry, CO residents can sue me, and anyone that aided me while concealing.  Took an UBER from the airport in NV?  The NV UBER driver can be sued.  Some abortion laws have similar language, they can sue people that left one State and engaged in a legal activity in another State.

"A cancerous tumor is made up a human cells and is alive,... should it be protected?"

 I'd say that since those cells are not capable of becoming "human life" that can engage external from the host, or exhibit sentience, then no they should not be.