The problem is the FDA wanted societal impact studies for the blue dye and nothing like that had been done before. It likely would've been an expensive and extensive undertaking.
Tilator- Keeping blue dye in will require a PH3 study. IPCI would still say that the blue dye is a good idea and may be in a product some day. But to skip a PH3 study(that would cost a few million) IPCI chose to remove.