On the face of it, that would seem to be unlikely to pass as a defense against an ADA claim.
It is interesting that LLBRY is saying that the videos were ‘made illegal’ (which isn’t quite true) without saying why, or offering to do anything about it. They’re saying ‘we think this is censorship’ but they are not saying, ‘we’ll pay to make this accessible.’ They are sidestepping the issue entirely.