Saying "I don't want to" would be a pretty abrupt response the first time you are politely asked for a favour - usually, we'd use more tactful language to say essentially the same thing. Or, in the case of a mass email request, simply ignore it.
Saying "I don't want to" after the *sixth* time someone asks the same favour of you, when you haven't said yes the first five times - that strikes me as pretty reasonable.
I definitely wouldn't have any problem with someone asking for something like note-taking from a fellow student when there was a need. But - what he's asking for is not a trivial favour, it's a fairly major undertaking. And it's something that not everyone *can* do. My notes are not legible enough for someone else to use, so me being a note-taker would result in either me spending more time on my handwriting, and none on paying attention to the content of the lecture, or having me recopy the material afterwards (a major time commitment). Either of these, done without compensation, would hurt my own performance. That's why universities often offer a stipend to cover this - it makes it worth while for some students to commit to doing this.
Then, when he didn't get a response, he proceeded to spam his entire class repeatedly. When someone outright said "No, I can't do that" he then got horribly offended, and called the person "rude beyond belief". The problem here isn't that he's disabled and needs help. The problem being discussed here is that he's repeatedly demanding a large favour from people, and attacking them if they say no.
A polite way - send a politely worded email to the class list explaining your problem and asking for help. If appropriate, any incentive (like a stipend) could be mentioned. If you wait a while, and there is no response, then a second follow up would be okay - in this one you could clarify that the occasional missed class, or idiosyncratic notes, are okay, and basically say pretty please.
If there is still no response, then it's time to go back to your university's disability services/ombudsman to discuss option, or to make alternate plans. Talk to the professor and see if it's okay to bring in a small recorder, so you can play back the lecture. Ask if it's okay to take a discrete cell-phone photo of the whiteboard/blackboard at intervals, to aid your retention of the material if you can't write it down yourself.