It indeed could but the complexity of changing Image Processor Pro dialog to include a newly designed optional move feature is infinity more complex then simply adding a step to an action that use a Photoshop script that has a hard coded move files in a source hard coded folder to a hard coded archive folder. It would also be very hard to change the Image processor pro script to not to display its dialog and hard code your your process. Its easy to doe is an action step. It something the script is coded to do.
The action only has two steps. There is no UI when the action is played is used. There is a dialog during the action recording.
Action Step 1 menu File>Automate>Image Processor Pro. You file out the dialog and click run the Plug_in script runs and also records the setting used in it dialog into the action step.
Action Step 2 menu File>Scripts>Move Source Files to Archive (A few line of java script)
The Image Processor Pro has 10,277 lines of code. To hard code that code to do your process and then move the source files would be and huge undertaking. A Simple hard coded move script is but a few lines of code.
The two step action a snap to record. Why make it hard.