My guess is just a QA burden: they probably test the firmware cleaner utility on those operating systems, and they don't have the resources to test and certify

My guess is just a QA burden: they probably test the firmware cleaner utility on those operating systems, and they don't have the resources to test and certify the firmware tool on every conceivable distro. Maybe it will run fine on Fedora, but if it bricks your laptop, they don't want to get blamed.