I don't mind the change, especially as the Davros story has been so told out now I doubt we'll see much on-screen for the foreseeable future. However, I would question if Davros would have seen himself as disabled. I'm not familiar enough with the canon to know if we ever learned why he was in the chair, but I always assumed that Davros had experimented on himself while working on the Daleks. Him being a transitory phase between the Khaled evolution and the future evolution that would become the Daleks. I saw his chair as a reflection of this mid-way Dalek.

As I said, I don't mind this change but I feel it is an ultimately empty thought if they don't have people with disabilities in the 'positive' roles too. It's all well and good saying he doesn't want to associate disability with evil, but that also has to be followed by normalizing folks with disabilities within other roles too.