If it's in their abilities to do so than why take it away from them? No matter how much work and time goes time it takes allow them too do so. I think not allowing them to do so is takes away from their independence, it's not a crime too allow them to try it
Students with severe disabilities should be allowed to learn more academics versus all day working on functional skills. Research shows increasing evidence that students with severe intellectual disabilities can learn to read or can at least comprehend text read aloud. Research also shows that students switching classes is beneficial for students with severe intellectual disabilities.