I'm going to let a blind man face plant into a huge concrete column.
Why would you let a blind man hit a concrete column?
If you want people to see what it means to be blind, then let them.
If someone is disabled and at risk of injuring themselves, you should help them out to prevent them from being injured. Rather than let the blind man face plant into the column, alert him of the danger so that he can revise his path. He won't be injured and will thank you for your help.
He isn't a child. It is good for him to learn from his mistakes.
How does him falling help him learn his lesson? That just seems cruel.