Fascism was an innovative political philosophy of early 20th century Europe. People who disagree with the most maximalist wing of trans advocacy can have a range of grounds for doing so besides the tenets of that very specific movement, which they may and likely do oppose; indeed their grounds may predate fascism, or stem from some other culture entirely, etc. But of course you don't throw around words like "fashy" out of any reasoned usage, but rather because you think that by associating your opponent with sonething outside the pale, inaccurate as that association is, you win the internets. People can see through this.