Best I could find is this: https://www.theguardian.com/commentisfree/belief/2013/dec/08... which implies it's an ethno-centric religion, so a hostile observer surely could call it "racist" (in an extended sense, where "racism" means exclusion by any ethnic origin, not just specifically the color of one's skin - just as antisemitism is commonly considered under the same term, even if majority of Jews it's directed at are of the same race as their persecutors).

Maybe, but I'm not even sure if there are many Zoroastrians left, much less whether they're racist or not.