This is a good thread to catch up on the basics, though I will say, I strongly disagree with the idea that being abled passing is what decides whether or not you end up in these workshops. I feel like it has to with smart/sane privilege more than anything. https://twitter.com/chaitofu/status/1351689400585838592?s=19
I'm obviously oversimplifying, but I say this as someone who has passed as abled before and definitely cannot now. I also find the concept of "passing" here to be quite nebulous as it's very fluid and based on abled perceptions.
And how much your access depends on the invisibility or visibility of your disability drastically changes depending on what your disability is. We don't all face the same kind of oppression and it can work wildly different ways for different people.