I agree, I am taking this way out of the original context, but I think the joke is maybe a straw breaking the camel's back here. I think Julia Serano's article communicates this well enough:

If one more person tells me that "all gender is performance" I think I am going to strangle them. What's most annoying about that sound-bite is how it is often recited in a somewhat snooty "I-took-a-gender-studies-class-and-you-didn't" sort of way, which is ironic given the way that phrase dumbs down gender. It is a crass oversimplification that is as ridiculous as saying all gender is genitals, all gender is chromosomes, or all gender is socialization.

She's frustrated, I'm frustrated. There is frustration that is generated by the "gender is just a social construct". The joke is literally about how the dumb cis people really just need an hour long lecture from an academic on how gender is actually just a social construct. I can't think of a better example of this condescending and ironically confidently-incorrect attitude.

Maybe I think too much, but I guess my whole point is that people are not thinking enough. When they say gender is just a social construct they may not be familiar with gender theory or understand the nuances, and maybe stamping out biological essentialism is worth the oversimplifying, but there is something that feels wrong to me about penalizing a trans person challenging a view that invalidates their gender as an arbitrary fiction. I understand the intentions are not to be invalidating, and that most people don't understand the consequences of social constructionism, but that's exactly why I'm raising the problems and challenging it.

To your point I could have done a much better job to not be confused with taking a biological essentialist view, but I think anyone who actually parses what I said and reads the articles I linked to will understand I am not endorsing biological essentialism. Still, that maybe is too high of a bar, and it would have been better if I did more to anticipate this knee-jerk reaction to my challenge. It's always good to make sure you are easy to understand, and this is admittedly a mea culpa because I was rushing and didn't have much time, so I wrote a much shorter comment and linked to articles to cover the extra ground for me (which was clearly not adequate).

I don't know what to make of your claim that I shouldn't interpret "gender is just a social construct" as supporting social constructionism ... there is something compelling here about what people are trying to convey is more rooted in their intentions than any kind of theory, like a lot of times when people tell me "gender is just a social construct" it's because they are trying to signal they are trans-accepting. That said, I don't think there is any consistent or coherent view that we could really point to then, that is I'm not sure we could say "gender is just a social construct" actually communicates "the gender binary is not valid", for example, because some people will take the social constructionism more seriously than others, some people use it to actually mean, "I think trans people are valid", and others use it to mean "I will tolerate you as a trans person", and others still might use it to mean "you are dumb and don't understand gender, but I went to school and in my anthropology class we talked about how gender is cultural and sex is biological, blah blah blah".

In summary, maybe you're right that I am inappropriately hijacking this joke to attack social constructionism, but I still don't think it's that crazy that I thought "gender is a social construct" was espousing some form of social constructionism.

Thanks for putting up with me and reading my responses, and for challenging me - you have some compelling points that I should think about more.