Sounds like someone with a little too much time on their hands and not quite enough sense. It's far too easy to pick on people on the internet. Honestly, Medium is the last place I would have expected to find people bullying others. You don't know me Robert, but I'm proud of you for doing your best work at writing. Dyslexia can certainly be a bitch, and any adult willing to write a whole article trying to tear you down for not being perfect needs some serious self introspection.
Please don't leave Medium. Don't let the bully, bully you out.