When he saved Justin by letting him see the Basilisk through his own body, Nearly Headless Nick was also affected. Did he see the Basilisk directly to eye?
What would have happened if he saw a Basilisk indirectly?
Canon doesn't tell us if Nearly Headless Nick looked directly into the Basilisk's eyes. It only tells us that Nick took most of the hit from the Basilisk, but that it's impossible for anyone to die twice:
'Justin must’ve seen the Basilisk through Nearly Headless Nick! Nick got the full blast of it, but he couldn’t die again ...'
Harry - Philosopher's Stone
As all the Basilisk's victims saw the Basilisk indirectly, except for Moaning Myrtle and, ostensibly, Nearly Headless Nick, using Harry's logic, if Nearly Headless Nick had seen the Basilisk indirectly, he likely would have still become petrified.