It's only an acceptable excuse if the original artwork files were lost or the actual icons were created in 32x32 pixel format to begin with. If you have the original artwork and it's on a suitable resolution, then in theory the exporting can be automated
But if you need to upscale 10k icons manually by hand, then you might as well rasterize them - redo them literally - to vector format so it's resolution independent (and be prepared for it to take months).
If the graphic engine requires bitmap - which it probably does - it's then trivial to batch export them to any resolution required.