The answer to that one is simple: Clinton's campaign and her media surrogates have spent nearly a year smearing supporters of Bernie Sanders as bigots. They've successfully placed the Sanders campaign under such a cloud of suspicion that nearly any smear, no matter how serious or implausible, will spread with no concern for the actual facts. Media figures have learned that they will not suffer any consequences for any lies or misinformation they spread, and that they'll be aggressively and belligerently defended if they face any criticism whatsoever.
Consider my previous reporting on the ridiculous Boss Hogg smear - another easily-debunked rumor of rampant bigotry among Sanders supporters. After that post received some significant media coverage, this is how the four people who helped spread that rumor responded:
- Emily Nussbaum, the rumor's source, admitted her mistake - while still insisting there is "an abrasive streak among some pro-Bern tweeters";
- Emily Cohn, who reported Nussbaum's false claim on Mashable, "clarified" her story by quoting Nussbaum's admission - leaving the rest of the piece unchanged;
- Jamil Smith, who linked to Cohn's article as proof of "misogyny" among Clinton supporters, approvingly referred readers to a piece that used scare quotes to cast doubt on whether his accusation had really been debunked;
- Kaili Joy Gray, who helped spread the rumor by linking to Jamil's piece, tried to ridicule Glenn Greenwald for reporting on this; even worse, she then tried to ridicule The Intercept for doing exactly what she should have done, admitting to a mistake. (And a completely unrelated mistake at that - "Probably a little bit dickish of me but oh, I forgot to give a fuck. Oh well." she said.)
The pattern is clear: Clinton's surrogates in the media will eagerly spread even the most ridiculous accusations of bigotry against Sanders supporters. If they are exposed, they will issue a token apology or "clarification" at best, all while insisting that the smear campaign is still credible. Typically, however, they won't even do that; instead, they will call the correction into question, as Smith does, or they will openly ridicule and attack their critics, like Gray does.
In this political landscape - where any accusation against Sanders supporters is presumed credible, any correction is disputed, downplayed, or ignored, and anyone who challenges any of this is ruthlessly attacked - in the media environment that Clinton's supporters have created, of course the "English only" smear is going to spread like wildfire. Just look at how eager all the usual suspects were to jump on this:
It's easy to dismiss this episode as a series of isolated and innocent mistakes - just a matter of people believing a rumor that turned out to be false. And in an utterly trivial sense, that's what happened here: Traister, for one, says that she simply trusted Huerta's account, and we can take her at her word.
But this abdication of skepticism and credulous belief in the bigotry of Sanders supporters is the utterly predictable and extraordinarily convenient outcome of a smear campaign that Clinton's media surrogates have been actively pushing for months. So when they spread this sort of rumor, and then plead innocent, it's a bit much to say that they've actually been fooled; the fairer way to put it is that they believed their own hype.