Prewar Army Signal Corps pilots did not even need a HS education. All they needed was a GED equivalent and to pass the flight physical and flight exam and solo. My dad, stationed at Wright Field right after WWI, said that many pilots were enlisted men and had little education beyond what I have stated. When the USAF was formed, then the rules changed, but even so, in the USAF, no pilot is enlisted and all pilots must have a college education but, this is still not so in the Army and Marine Corps where enlisted, non-college pilots are still in action.
I have not known of any dyslexic pilots per se, but do know that a lot of very highly educated people are dyslexic. Ignorant people can come in all types. There are some PhDs that wear aluminum helmets.