The Soros conspiracy theory is literally the latest version of an old anti Semitic trope. Many eras of visible anti-Semitism have a figurehead evil rich Jew pulling the strings, be it a Rothschild, Max Warburg, whatever. Others just settle for making socialism a Jewish conspiracy instead.
The mainstreaming of what was originally a fascist canard, one that's been peddled for years, doesn't change its origins. Recycling stuff the Daily Stormer has been pushing for a decade or more doesn't stop that claim from being a nazi dog whistle. It just makes the more mainstream regurgitators of the conspiracy theory into accomplices and dupes of the far right.
And if "nobody who supports Trump" will accept the nazi origins of their anti Semitic conspiracy theory, then that literally just cements them as, at the very least, entirely comfortable with being fellow travelers helping to promote anti-Semitism and strengthen the far right.
But then, we already knew that degree of comfort was a thing. There is, at this point, a well worn path by which nazi conspiracy theories and propaganda work their way into the rightmost elements of the political mainstream.
It's why literal neonazis can get an uncritical airing on cable news, why government senators in Australia can vote to support a motion condemning anti-white racism and affirming that "it's okay to be white". It's why old concocted nonsense like "the genocide of white farmers in South Africa" is getting a run with Fox and Trump.