Context is key. I haven't followed this shirt brouhaha in any serious depth but I assume that all of his colleagues and management saw him wearing the shirt before he delivered his talk. AFAIK it became a problem afterwards. So, if you (not me) want to equate a shirt with female characters on it to a shirt with the N-word on it then, yes, if the workplace context was right why not wear it at work (e.g. I'm thinking an indie record label or similar environment with black, white, whatever people working together as a tight team and a black friend of a white guy bought him said t-shirt).

Ultimately, it's up to the guy wearing the t-shirt to make a judgement call as to whether doing so would offend or not offend his friends and colleagues. So: context, relationship with everyone else at the place he works at, balanced sensitivity etc.

If he honestly (not deliberately) makes the wrong call, he should apologise and everyone should move on. Work is a place for adults, not children on a lynching party.

If you're white, and your black friend gives you a shirt with the N-word on it, they aren't your friend.

These guys are probably friends.

http://realfunny.net/picture-3097-these-two-friends-wearing-...

They probably don't wear the shirts to work.