How is that an impediment? Are you saying a person with dyslexia is incapable of authoring a resume that makes a good first impression? I disagree.
Dyslexia does not preclude someone from doing a good job at all. Spell check. Use grammar tools. Get someone to proof read. Not that hard.
If I were interviewing someone who told me they have dyslexia and their resume is perfectly written, I will know, without a doubt, they will be detail-oriented while on the job. Once again, the resume is a valuable opportunity to make an excellent first impression.