Yes, let’s pretend the cut isn’t punitive.
What you propose is done all of the time. Indirect costs are proposed, rationalized, defended, and reviewed constantly.
How does a single number like 15% for all unis get generated? It was arbitrary. Prove otherwise.
Scientists and universities: defend indirects as a concept but not current indirect rates. Don't think there's waste in those numbers? We (US science) spend $4.5 billion on journals. That is HALF of the proposed cuts in indirects, and eliminating that spending would make science better!