I don't even understand why the character needed to be an amputee anyway. The odds are already against him, so why gimmick it further?
I, too, wonder where the line is going to be drawn. This isn't as obvious as blackface or Pacino doing a terrible Cuban accent, it's a little more nuanced in the case of trans/LGBTQ actors. Scarlett catching flack annoyed me because Tilda Swenton played a man and nobody cared, so this is where I start telling kids to get off my lawn.