I can certainly understand why anyone opposed to abortion on religious or moral principles objects to embryonic stem cell research.
The potential that abortion material becomes something of great value that actually encourages abortions for profit is obviously there.
STill abortions are happening, anyway, so the argument that just throwing away that material is just wasted otherwise can be a powerful argument in its defence, too.
I'll have to ponder this debate a while.
I am of the opinion that should embryonic material become truly valuable as a clinical tool to save people or cure them, then it WILL cause some people to encourage abortions for profit.
Off hand I'd say that the probability (under the above circumstances, at least) of aboreted fetuses not becoming a coveted item is practically nil, IF, for example, that material can be used to make cripples whole again, or to save lives of people who might benefit.
This IS a very difficult issue to resolve if you are, as I am, not opposed to abortions based on the principle that every woman has the right to decide for herself whether to bring a human into existence.