This is dangerous territory.
First off - you are assuming that unborn human beings have no intrinsic value.
You are correct. Something without a mind doesnt have an intrinsic value nearly as high as something which does. Everything has some value, but that value changes depending on its characteristics. If I have to chose between making a woman miserable or killing an embryo without will, feelings, sensations, emotions and social bonds, the choice is easy. One can be harmed, can suffer while the other cannot.
Second - not all adult human beings are "conscious" all the time - does that mean I can legally kill them when they are unconscious?
No, because it goes against their will. The will of a person extand beyond temporary lapses in consciousness. Unconcousciousness doesn't suspend social bonds and roles either and often doesn't even suspend all sensations and feelings. The Prime Minister of Britain is Prime Minister even when asleep (or emergency care as he is right now).
There are some adults who do not experience emotion - I can kill them too?
Citation for that. I don't believe there are humans without emotions. There are humans without empathy or feeling of pain for example, but they have emotions still, not just all of them.
And no, even if there were such people, you could not kill them because they still have sensations and will.
I can kill any and all "shut-ins" or "hermits" because they lack "social contact"?
There are no absolute "shut-ins" without any social bonding abilities and they still have will and emotions so they have value and a right to security.
Don't expectant parents "bond" with their unborn children?
In most cases yes, but not in the case where those embryos are aborted. It's also a parasocial relationship too since embryos do not gain consciousness of their surrounding until the 24-28 weeks period, well after the point where embryos are electively aborted (that means without medical reasons).
Unborn children have no "social role" to play? They don't affect anyone's lives? Alter the decisions they make?
They don't have a social impact, but not a social role. They do not produce anything or participate in any active way in society. Even babies participate to our social lives and society if only in very limited ways, but embryo don't.
Basically - any excuse you use to justify the murder of the unborn can be used against the already born.
As I have demonstrated above, this is a false statement.
Only if chia seeds eventually turned into dogs.
Until the chia seeds turn into a dog, it shouldn't be treated or viewed as a dog. Just like children should not have the right to vote because one day they will be adults. Embryo shouldn't have individual rights and personhood until they actually start to display personality, will, emotions, sensitivity and consciousness which is, at the earliest, around 24 week of gestation when the neo cortex develops.
If a woman wants to have her unborn child - it has infinite value.
If a woman does not want her unborn child - it should have no value?
In an overly simplistic and caricatural way this is fairly correct. If a embryo isn't conscious, doesn't feel, doesn't think, doesn't have will, doesn't have social contact, doesn't have independant metabollic capacities, it should not be viewed as a person and doesn't have anything that makes life truly special, unique and valuable. It's only value is thus granted by those who carry those embryo. If they aren't desired, they can be killed just like any weed. If they are desired they are given a value by the social attachment of the mother. It's the a bit the same thing for any object taking an abandonned sock isn't theft, but taking the sock of someone is.
Abortion is murder. It makes no sense any other way.
It makes no sense, in my opinion, to qualify of "murder" the killing of something with an awareness and emotional development comparable to a grass. A newborn baby is so far more complex and aware than a 12 week old fetus that trying to compare one to another is an insult to a baby's capacities.