The reality is that regular size, line-of-sight, R/C planes and helis are not large enough to carry a threatening payload. I don't think that "terrorists" intent on harming the U.S. are really taking the R/C model airplane concept seriously. Hopefully clearer heads will prevail in our government and lawmakers will realize that these fears are unfounded.
But, if something tragic did happen, perhaps they should make a law banning ARFs? I'm not sure those terrorists can build a kit