If the argument against fetal stem cell research is based upon the view that destroying the embryo (as a result of conducting scientific experiments on it) is the taking of a person's life, then this assumes that it is murder. It also follows that destroying the embryo without using it for scientific experiments is murder. Similarly, the view that all abortion is murder follows (as long as you assume, as I do, that there is no successful defense against this implication based on the right of the mother not to have a parasite use her body.)
So, the argument against stem-cell research has to assume that the brainless cells in question are people, if the argument is about murder. This is a difficult position to maintain, given that many cells are similarly brainless yet not people: liver cells, skin cells. And these also can get brains with the cloning technology we will get in the future. Or, at least, the contingency of technological possibility there should not matter. Even if the technology is forever beyond us to clone a person with a brain from a liver cell, it is in principle possible, as possible as it is for an embryo to become such a being. In short, if brainless embryos are people, then all human cells are people. Both need certain conditions to bring about the fruition. Both have very similar, complex internal mechanisms that will bring it about under the respective conditions. That the embryo is an organism does not appear to be relevant.
On the other hand, in this connection the amount of medical research that could come from fetal stem cells is irrelevant if the embroy is a person. We may not kill people for medical research. So, the appeal to medical usefulness is misguided. Still, though it's misguided, it is aimed at a weak argument: that destroying a certain kind of cell is murder.
If, on the other hand, destroying an embryo is not murder, then neither is abortion in the stage before there is brain tissue. Perhaps, rather, the argument is that it is just immoral to destroy human organisms even when they are not yet people and do not yet have brains. This is a reasonable argument. There is something unseemly about destroying human fertilized eggs. It may even be immoral, after the fashion of buying great art, taking it home, and burning it for fun. But whether this should be illegal is hard to say. It's an open question, though I would not be in favor of this infringement of liberty when what is at stake morally is not clear but merely "unseemly."
To this argument, the medical usefulness of fetal stem cells is relevant. But again the argument from unseemliness is anything but clearly well-founded. Why bring up the extraneous matter of the usefulness of scientific research? How can you weigh the value of the future, unknown research against the value of keeping non-person human organisms alive? These are imponderables.
So, the debate is uninteresting to me. None of the arguments is interesting. Only one has obvious weight, namely, the argument that a cell without a brain is not a person and therefore cannot be murdered. So, I'm not interested in the topic. By all means, default to liberty here and oppose prohibitions on the research. And cutting off government funds is close enough to such a prohibition as long as our medical research system is as socialized as it is.