I have absolutely no concern over a 20 yr old's ability to weather the rigors of manipulating a 7 gram pencil. It's not like we're talking about getting them to spend a week on a roofing crew or swap their gaming mouse for a set of post hole diggers here. If someone needs an accommodation then that should absolutely be made available.

I'm all for handwritten tests, but it's more complicated than that. If you're actually writing for 2hr+ and haven't studied appropriate technique or bought some sort of crutch like a pencil holder then the repetitive motion will absolutely cause cramps for a fraction of the class regardless of being 20ish and healthy, and they might not find that out until they're forced to write for 2hr. The muscles manipulating a pencil (with poor technique) are much smaller than those manipulating a post hole digger, so that comparison isn't fair.