So no, don't bring it up.
She saw a dead stranger in his car, big deal ~
She does not need your help to get over it.
Shoe on the other foot, what if it was the man being like "She can't handle hearing about something like this"?
If she couldn't handle it, she would not have told her friend to keep quiet about the incident.
She would have gone straight to the boyfriend if she needed his support.
So if a man says a woman can't handle hard news, and didn't go to her for support, you'd agree with him that she must be too weak to know about it?