A few things,

First of it it's horrible you were fat-shamed. That is not okay, and clearly a troll did that. I don't care what their political officiation is, it's not okay that someone wrote that.

I do feel your tweet was rather transphobic, and I think it's okay if you take ownership of that. It will piss people off. However I can see how her angry response cut down the conversation. I mean you have a point, we need to have conversations. However be careful because when you add into a conversation something really offensive or hurtful, it will shut it down, and you are actually the one shutting it down- not them.

For example, if I wanted to start a conversation about the rights of jewish people and started saying things like how how doomsday they are and they should all just get over the holocaust it wasn't that bad, I'm sort of setting up the conversation to fail, especially with jewish people or anyone who cares about them.

Let's say I wanted to just start a conversation about men. Maybe I would start off the conversation by proposing the idea society should keep boys and men in concentration camps, harvest them for their sperm, then terminate them after say age 19 for the greater of society because we don't really need them and should they even have the right to live? I'm sure that's a conversation many men would become understandably angry at. I imagine some men may not even have the energy trying to explain to me why they are entitled to the right to be alive. Having to argue that you should exist can feel very demoralizing. So for many people, explaining to people over and over again that they should be entitled to exist can feel so exhausting that their self care is to just stop for a minute. Now this is a rather extreme example, but considering the number of trans people who are murdered yearly simply for being trans, as well as politicians and other people pretty much wanting trans people to not to be trans, or having health care (which can lead to death), it's not that far off. So while it's important to have conversations, it's also to do so in a way that invites people to contribute instead of alienates them. Starting a conversation in a way that is alienating, isn't really starting a conversation.

As for moving the goal post, I'd say it's a bit more complex than that. Once we meet a goal, it's okay to set up another one. As a teacher, last week I taught my students about parabolas and then next week they learned the quadratic formula. Is that moving a goal post, or is it just growth?

For example, over 100 years ago, women were fighting for the right to vote. But they weren't even allowed to have their own bank accounts (and thus money) wasn't allowed until the 1970's. Is that moving the goal post? Or should we have just stopped at voting because after the vote we were all equal and fine?