"The flaw in your argument is that it assumes a clear and workable distinction between "a joke" and "obvious hate speech" That is usually easy derived from the

"The flaw in your argument is that it assumes a clear and workable distinction between "a joke" and "obvious hate speech" That is usually easy derived from the context and the cases I know of "missunderstanding a joke" was rather deliberate misinterpretation of the law to get someone out of line. Your example seems like this as well.