Intent doesn't really... matter, is my point. You are still furthering the idea that hey, its ok to make fun of these people, which can fuel others' bigorty inadvertently, and that's not okay. I don't care how well you mean.
She's saying there's no shortage of excuses to be mad at what people do accidentally and that when you do, all you're doing is increasing the general level of hatred. If you actually want things to change, you have to be conscious of intent.
A person who unthinkingly makes a racist joke is going to be doubly vigilant to never make another racist joke. A person who knowingly, willingly makes a racist joke needs to know it's not okay to do that around you. Both people will have their behavior shaped but the approach taken must be directly opposite in either case.