I know quite a bit of people with dyslexia or reading/writing/language disabilities. Writing extremely long messages is not a typical thing for them at all.

There’s nothing wrong with you sharing that your sister is unwell. But unless your friend is your sister’s doctor I think sending detailed descriptions of her legs and pictures of them is a bit extreme. I think he was polite about it but didn’t know what he was supposed to say. It’s a bit awkward.

As about poop you do need to pick it up regardless if you have bags or not so he can’t really validate you on that because you are in the wrong.

Message about sisters legs was too long but he did plan on reading it. It’s a nice thing on his part

Making fun of you about “essays” isn’t very nice but I guess depends on the context.