The only way to lessen the impact would be to colour correct it before dropping it back to 8bpp really. Or at least decide on the gamma curve and apply that before dropping to 8bpp.
I don't know any colour grading software that doesn't work in at least 16bit, what software is he using?
The captures are actually in 16bpp not 10bpp, I capture video in 10bpp, but film is usually 14bit or 16bit.