Dean Stretton imagines a case in which an emergency arises and a person is faced with the choice of rescuing ten frozen human embryos or five adult patients. Since virtually everyone would choose to save the adult patients rather than the embryos, this indicates that the patients have a higher moral status than the frozen human embryos. 
On the surface this seems to make sense. After all, the pro-life case is that from fertilization unborn human beings are morally equivalent to adults. You would think the ethical thing to do would be to rescue the greatest amount of humans possible, in this case the ten embryos.
However, these embryos have been conceived through IVF. That means we have no idea what's going to happen to them. They may be implanted into a woman hoping to conceive (or several different women), or they may be used for research. This is tragic, but we simply don't know the ultimate fate of these embryos. On top of that, even if they are scheduled for implantation, there's no guarantee that all of them, or even any of them, will take. They may not implant. Therefore you would be morally justified in rescuing the adults, even over a greater number of human embryos.
Consider it like a case of triage. Two people are in mortal danger and a doctor can only save one. The doctor will save the person with the greatest chance of survival. Does that mean the other person is less valuable than the person she saves? Of course not. But if she tried to save the person with the most extensive injuries, she may end up losing both. In this case, since the fate of the embryos is uncertain (nor could it ever be certain), saving the adults would be morally justified because they have a 100% chance of survival if you rescue them.
But what if you take it a step further? What if you knew for certain that all the embryos would be given to women, and technology has advanced to the point now that we can guarantee that all, or at least the vast majority, would implant.
I still would not change my answer. First, if there is a genuine emergecy (say the building is on fire), I'm not going to waste time trying to read the label or find the paperwork to ensure that these embryos were scheduled for implantation. I'm going to make the most logical, life-saving choice and still save the adults.
Second, how would choosing to save one entity over another prove that the entities I didn't save aren't human? In fact, we could change the conditions of the scenario. Say you're in a burning building. In one room is your mother (or choose any other living relative), and in another room is a complete stranger. You only have time to save one. I would almost guarantee you would save your mother. But does that mean the one you didn't save wasn't human?
Third, even if we were told ahead of time that these embryos were scheduled for implantation, we would still be morally justified in saving the adults. As Christopher Kaczor explains,
"...killing a regular person and killing the President of the United States are equally wrong as killing. The regular person and the President have equal rights to live. However, unlike killing a regular person, killing the President may also generate global instability, upset millions of people, and perhaps even prompt massive retaliation or world war. These factors make the assassination of any world leader more grievously wrong than killing a private citizen, but, nevertheless, killing the President and killing a private citizen are equally wrong with respect to the violation of the right of life...we have moral justification for treating human beings enjoying basic equal human rights in different ways. If forced to choose between saving the President of the United States and four other national Presidents and Prime Ministers, rather than ten unknown patients, most people would choose the Presidents and the Prime Ministers. To choose to save Presidents and Prime Ministers rather than plain persons is not a denial of the equal basic rights of those not saved, but rather a recognition that deaths of world leaders adversely affects many more people than the deaths of regular patients. Similarly, in virtue of the fact that the adult patients have received an 'investment' from their parents and society in terms of education and upbringing, have future plans that would be thwarted, have responsibiities to discharge, and have strong relations with others, it makes sense to choose to save five adult persons rather than ten frozen embryos. In choices about who to save, various circumstances can determine who is chosen without a denial of the fundamental equality of the human beings involved. The embryo rescue case does not show that human embryos lack basic human rights." 
Pro-life advocate Scott Klusendorf notes,
"...moral intuitions are important, but they are not infallible. We must examine them in light of reason. A little over a century ago, many whites thought it unthinkable that anyone would consider black slaves human beings...Thus, it's no stretch to imagine a proponent of slavery putting the following challenge to a northern abolitionist: 'Your barn is burning. You have the choice of saving a Negro slave or a white schoolboy. Which would you choose?' If a majority of abolitionists leave a black kid behind, does that change the kind of thing he is...?"  In other words, is the black slave non-human even if a slavery abolitionist would leave him behind to save the white schoolboy?
 Stretton, Dean, Critical Notice--Defending Life: A Moral and Legal Case Against Abortion Choice by Francis J. Beckwith. [review article]. Journal of Medical Ethics, 34(11), p. 795, as cited in The Ethics of Abortion by Christopher Kaczor, Routledge, 2011, p. 139.
 Kaczor, Christopher, The Ethics of Abortion, 2011, pp. 89, 139.
 Klusendorf, Scott, The Case for Life, p. 42.