I, for one, am glad to see this. As someone who admittedly used to make occasional jokes with friends about this (though really only if other people started joking about it first), I was glad that as I came to know more people in the trans community and people who identify strongly as allies as well, I was educated about the damaging effects of these jokes and the terrible stigmas associated. Part of life is the personal growth of discovering new perspectives to different topics and learning about the different issues plaguing those of different identities and cultures. For those who used to make jokes and feel as if their speech is going to be incredibly censored, I ask that you, instead of expressing your annoyance or frustration immediately, take the time to have a discussion with someone who strongly opposes your position or do some research on how these jokes affect trans people, most specifically those who are MtF. Perhaps weigh the importance of being able to make a joke or use a word in certain contexts over the importance of people of a marginalized group feeling safe. Yes, most people understand that the word's use in the context of jokes isn't particularly the same as calling someone by that name and therefore isn't particularly targeting someone, but what it does do is contribute to a stigma that people with genitalia differing from their outwardly presenting gender are undesirable and/or demonizes them by implying they wish to deceive others. In my opinion, if me simply removing a word from my vocabulary in certain contexts has the contribution of decreasing the stigma against trans people and by association, easing their already absurdly plentiful and ridiculous struggles by even a fraction of a percent, I'll gladly do so.
There are derogatory words targeted towards those of asian descent. A simple google search would find you results on that. And perhaps instead of asking "what word we're gonna use," perhaps consider the alternative of not making jokes at the expense of marginalized groups. I hope that approach may have more fulfilling results for you.
Don't take my word for it since I'm not a staff member, but I think it would be safe to say those words in those contexts won't fly either. From the experience of being the person who originally wrote up the post regarding rule 4, we tried to make it clear that variations of some of the listed words were considered bad as well, considering we all know the words themselves aren't dangerous, but rather their societal connotations. Of course these words aren't entirely banned as they are words that didn't originally begin as derogatory terms, but I'd assume that in the specific context, they'd also be frowned upon.