Dyslexia is not an excuse not to learn grammar. My son was just recently discovered to be dyslexic, he's only seven and it distressed him that he couldn't keep up with the other kids in terms of reading. Now we know about we can work on it. I've been working with him using a book for dyslexics and it's clear where his difficulties lie. Otherwise he's very talented intelligent, well above average.
Being dyslexic is not an excuse for anyone. It's a genuine problem. I thought we'd left that kind of attitude behind long ago.
While it was long ago and many things have changed for me the best thing that happened was a teacher gave me a reading card! He actually made it and all it was was a card with a slot cut into it so I could only see the sentence I was reading,no words above or below were seen and I could almost read aloud as well as the other students. I still had difficulties with articles and pronouns but at-least most could finally understand what I was reading.
Doing long division also caused problems,I got the correct answers but when I showed my work it never made sense!
Some of the worlds greatest thinkers are thought to be dyslexic, I first learned about it from of all people Tom Smothers,Dr Joyce Brothers noticed he used both hands and said that was a classic sign of dyslexia,Tommy said well I've always been abit different! This was in the early 70's and it was all but unheard of! Myself I cant tell left from right without conscientiously thinking about it,I have to envission which hand I throw with because I know that's my left,by the way I'm right handed,well I write with my right hand,shoot a rifle left,a hand gun right,etc. Oh and I kick with my left.......

PS: I have never used it as an excuse! If anything I was ashamed of it as a youngster!