Learning disabilities, per se, is not a disqualification for military service.
People with learning disabilities are prosecuted for crimes all the time. The percentage of people with learning disabilities in jail/prison is probably higher than in the general population.
Obviously, people with learning disabilities have the same ability to make correct choices than
people without them. Sometimes, people with learning disabilities are even BETTER in certain things (e.g., fixing things) than "normal" people.
Where did you get the idea that people with learning disabilities are "defective" in some way? They are not. They just have a different learning style. They have strengths and weaknesses just like anybody else.