I don't do much InDesign scripting but I think that changing the size or resolution of an image after it has been placed in InDesign does not change the size of the placed image. At least that is the it works if done manually in the GUI. Edit a placed image using the InDesign links panel, resize, and update. The the actual resolution of the placed image may change but the size of the image in InDesign does not change.
You need to resize in InDesign or both Photoshop and InDesign.