I don’t think I’ve used the word abusive here, forgive me if I’m wrong.
No, helping a dyslexic person learn to read isn’t abusive. ‘Zero tolerance’ of alternative ways of communicating would be. Insisting that they must read without adjustments they need such as coloured filters for Irlens, chunking information, dyslexia friendly fonts, etc and insisting that their refusal to read is ‘bad behaviour’ would be.
Insisting that someone with ADHD organise themselves and providing no accommodations, no visual prompts, no medication, no neuro-affirming coaching would be abusive, yes. If the person with adhd is overwhelmed, supporting them to organise themselves would be helpful, as long as it’s done in a way that supports their neurology, not works against it.
You also can’t do these things in a state of high arousal and sensory overload. A period of backing off on the reading / organising etc is likely to be necessary first if that person is already overloaded.
Of course, the people with dyslexia and ADHD might also experience sensory overload and meltdown / shutdown, those things aren’t just the preserve of autistic people.