It's more than opponents of wars, for example, are allowed. Even the burden of this compromise is heavy on those awaiting the tremendous promise of stem-cell research. That promise has already been delayed for years by the congressional ban these new rules are designed to accommodate. The breakthroughs will be slowed by more years because of all the elaborate safeguards built in to protect those clumps of cells. Imagine being paralyzed by a spinal cord injury in your teens, watching for decades as medical treatment progresses but not quite fast enough, and knowing that it could have been faster.
Absolutism is their logical trump card.
But absolutism is also a great weakness, because it puts you at the mercy of your own logic. A goldfish resembles a human being more than an embryo does. An embryo feels nothing, thinks nothing, cannot suffer, is not aware of its own existence. Embryos are destroyed routinely by the millions in the natural process of human reproduction. Yet opponents of stem-cell research would allow real people, who can suffer, to do so in service of the abstract principle that embryos are people too.