Sigh... telling a racist joke to a group of white faces would still be an ignorant thing to do if the MS wasn't married to one of the minorities in said joke.
Conversely someone making a similar joke about their own background is a totally different context and doesn't have the same intent. And like KevinB said a lot of people use humour as a way to cope with terrible things, or relieve stress after surviving dangerous situations.
Sure, impact of a joke definitely matters, but so does context and intention. If your only take away there was the MS was offended because of their spouse, and that's why it was wrong, you missed the point. Some things you save for the mess because that's the audience that will understand what you are talking about, not because its some kind of free fire zone with no rules where you can say racist, misoginistic or generally awful shit with no consequences.
Culture is always changing so adaptation is a constant thing, not a 5 phase operation in SMESC format with a defined beginning/end. People are coming into the CAF with all kinds of inherent biases, points of views etc, and can shift and change as they meet new people, get exposed to new things etc, while others come in as assholes and stay that way. Zero tolerance sounds good but doesn't leave any room for genuine misunderstandings and all sorts of other typical social interactions where there was no intent to offend.