TERF has come to mean "any woman who won't enable my delusions and impulses". There's a reason they go so hard after the radical feminists, as the radfem ideology in its current form sees trannies as part of the patriarchy, thus part of what they consider to be an institutional and familial problem. Radfems also hate porn. These troons have mother complexes and thus women are seen in the most black/white way. They're either good enablers, or evil nazi garbage TERFs. They're no in-between. It's much like the incel view of women. - how they all have an idealized projection of how a woman should be, but they can never find her in reality, and the more narrow it is, the more they resent all women who don't match up.
Men who shit on troons are never on the receiving end of so much seething rage as when "TERFs" do. There's a reason.
Troons are all puer aeternus males, and part of being puer aeternus is having a mother complex because, generally speaking, their mother was either too smothering / emotionally consuming (helicopter parent), or the opposite, neglectful, distant and scornful. Both these extremes shape how they view and understand women and they develop a mother complex which cripples them. One way of dealing with such intense confusion about the opposite sex is falling into this cultish ideology which tells them they can BECOME their ideal girl ("couldn't get the girl so I became the girl" meme is deeply true). And next to that, since they're hardcore narcissists who are basically empty inside, they need enablers who they can walk all over and get validation from. That's their ideal mommy figure, and some probably had mothers like that. That's the typical liberal feminist becomes a surrogate for, who sees them as innocent children who need to be protected at all times. That's what they want. They want to be protected in a metaphorical womb by maternal-like smothering. So just imagine what the opposite is.
The opposite is what "TERF" has become to symbolically represent. TERFs represent everything negative about women, wrapped up into a neat box which they can project onto anyone for any fault. Because they're narcissists, its anyone who doesn't enable them. But worse than that is feminists who actively work against their cult tranny ideology, as it makes them doubt their very existence. Just observe the way they talk about TERFs, and you notice how most of them sound like a dumb kid trying to rebel against their strict mother.
TERFs piss them off so much because, being feminists, they're the kind of women they feel SHOULD be enablers, but they're not. They care less about conservative rightwing women for example. The most evil TERFs to them are the ones who they feel entitled to having as handmaids
Troons resent humanity, including themselves (transition is a form of self-destruction) but to them at least their supposed "allies" serve a purpose and enable them - they absolutely cannot deal with the fact that a woman, especially one with a feminist ideology, refuses to accept their narratives and worldview and sees them as the manbabies they are. That't not to say TERFs aren't also supremely fucked in their own way because they are, but its not because they "mean" to trannies.