Someone please tell me the logic of Bush using his first Presidential Veto in six years to stop stem cells....

...that are going to be destroyed from being used to help cure disease? Stem Cells have shown so much promise in treating disease. (e.g. Huntingtons, Alzhiemers). The only answer I can think of is he's cowtowing to the religious right, and the Republican Party. I honestly hope someone close to him never gets a disease he could have helped prevent as I have. Please, anyone tell me the logic behind Bush using his first and only veto for this purpose.