They may not be willing (so far) to participate in the Science Debate, but at least they are addressing the questions being asked to them regarding science issues. So far, Barak Obama has outlined his science policies, and we are still waiting for responses from John McCain.
I'm actually not surprised that the McCain camp has been slow in responding. From all that I've read earlier, I don't think he puts science and science issues high on his agenda and importance (just like the rest of the general public, I suppose). Both Physics Today and Science had done analysis on the candidates' view on science policies, and John McCain had the vaguest and least well-defined policies of all the major candidates during the primaries.