My point (as you obviously missed it) is pretty simple. Just because someone makes occasional spelling or grammar errors you can't assume them not to be a highly educated professional.
From personal experience however I can confirm that the vast majority of the pedants I have met over the years have also been utter morons and usually no where near as intelligent as they profess to be. Their pedantry appears to be simply the manner in which they compensate for their other failings.
So you're saying I'm not allowed to make assumptions about people who have bad spelling and grammar, but you are allowed to make them about people who have good spelling and grammar? And that your assumption is that they're "utter morons"? Riiiiight
I think you might need to revisit your dyslexic diagnosis, perhaps you are just thick
I would say that most doctors are probably able to differentiate between there and their and your and you're, although perhaps not all. Yes, it could be that this guy is in that minority, but in my opinion it's more likely that he's a fibber. Just as it's unlikely that a doctor would post that he is a doctor as it's something of a sensitive profession for a punter.