Dyskinesia is an umbrella term encompassing a range of different movements. These are all movements that can be out of your control. Dyskinesia is very common in cerebral palsy.
Cerebral palsy is an injury to the brain, but what we find is that it has a lot of effects on how you use your muscles.
Every educator needs to make a decision about technology they need to put in place. They're not sure if they should put Option A in place or Option B in place. This can be particularly difficult in the world of disabilities because there might not always be a perfect answer. Teachers can look to this solution, using the least dangerous assumption to make good decisions about what technology might be best.
When you don't have enough evidence about a student's performance, assume they can do whatever you're asking them to do.