First off, Jack asked Mary if she wanted to see the photo. She said yes. He said it was racist, yet she agreed to look at it. While she had no idea or not if it would offend, it was her choice to look at the photo.

Honestly, I've had coworkers ask me if I wanted to see something funny and have had them show me digusting stuff on their phones. They thought it was funny, they asked me, I agreed and even though I found it gross, I could've said no or asked what it was before looking at it.

Likewise, I've had people text me disgusting stuff thinking I'd find it funny and I didn't. I just hit delete and that was it.

I wouldn't say anything. Sometimes you can never know what you might find funny might be offensive to someone else. My guess is that's how Jack felt.