The english language does not have a language council at all, and any way of speaking or writing is seen as correct if used in a cultural group or a society. Yes, there is a norm set for the linguistics but if you study english at university level you will learn that non mainstream grammar, spelling and so on are acceptable.
Or maybe people can actually acknowledge the real reason as specified by the person in question, that being severe dyslexia. Now, I'm not sure about you guys and gals, but I sure don't like being a jerk to those with any sort of disability who still at least try to perform those tasks inhibited by said disability (like a severe dyslexic commenting on awesome comic strips, for example). It's like the fat smelly kid from Freaks and Geeks: "it keeps the jerks away and the nice people don't care."
The real question for me is, shouldn't we expect a native speaker of a language belonging to a literate society to write it correctly? When children make mistakes, we lovingly reprove them to help them learn. But when adults screw up, it's simply "no big deal" and such mistakes should simply be ignored? Bah.