One of the most commonly ignored unsafe conditions in a facility is the unsafe coworker. There was a time when safety violations were “for management to deal with.” If Bob didn't wear his safety glasses, it was up to the supervisor to say something.
Now stop and think about how many blind electricians you know. Did you think of any?
There is something wrong with how Bob is “wired” if he won't use a simple measure to protect such a precious asset as his eyesight.
The problem for you is not that Bob could be blinded — it's that Bob's attitude makes him a danger to others. If he won't protect his own eyes, what other unsafe acts will he commit? Can you truly trust him to properly verify de-energization as part of lockout/tagout? How can you be confident he won't create an arc blast by improperly taking a voltage measurement?
Don't ignore an unsafe act. Ask the person to stop and then to tell you what he can do differently to be safer.