Yes, Helen Keller was wrong when she wanted to deny a paralyzed child surgery. But if we are going to judge her by 21st century standards, we should also judge the time she lived in by 21st century standards:
1. There was no real social safety net
2. There was little in the way of rehabilitation for people with paralysis
3. Social attitudes were different. The kid would have been shunted into an institution after a childhood (maybe) spent in special ed classes that did not challenge him.
4. Marriage, career, children--all things this paralyzed child would probably have been denied. Not to mention the lack of handicapped-accessible spaces.
5.. Helen Keller was very open about saying that she was able to achieve what she did because her family had money and could hire a private teacher. If this other child's family had no money, his life would have been difficult in the extreme with no hope of a teacher or real education.
Yes, Keller was wrong. But she came to this incorrect opinion in part because she was realistic about the type of life the child would have had.