Oh please. The "there are worse things" fallacy is so old there are books on it. Even specifically on the case of "discrimination of women is not as important as whatever-is-deemed-important-by-dudes today".
>Frankly, if the word on that picture had been a racial slur, many of us there that day would have [walked out].
It attempts to draw an equivalence between the two. You have reinforced that with your post above. I dispute that, for much the same reason I dispute that 'moron' or even 'retard' is in the same category. Simply, 'bitch' can not be used in the same way as a racial epithet. This is not a fallacy, and while there certainly are worse things that's not at all what I was getting at, and finally none of this has anything to do with 'whatever-is-deemed-important-by-dudes' or such nonsense.
At any rate, this wasn't even a joke. How is it funny? How could anybody think it would be funny? I don't even mean it isn't funny because it's offensive or not, it simply isn't funny full stop. Noah Kagan has a poor sense of humor, and should not attempt to make jokes.