That's the Paradox, they use tolerance to fill the space with intolerance.
I said it in a comment below and I'll write it out again because it is a great point (that I have seen several times on Mastodon, not that I thought up on my own) that the only way to resolve the Paradox of Tolerance is to understand tolerance as a social contract.
Nazis start from not adhering to the contract, because they refuse to tolerate certain identities. TERFS refuse to tolerate trans identities. Neither the Nazi nor the TERF viewpoint is entitled to tolerance. Compare to Furries, who have no problem with non-furry identities but are often not welcomed because they are so very very strange. Tolerance is for furries, not nazis.