No shit. He started on immigration (very relevant) and soon began questioning exclusively about latin American political matters. Bernie openly said he's rather not talk about that, and the guy still kept asking questions. "I'm not well informed enough on this to answer you" is a completely honest and understandable response.
Yes, if he was being interviewed on Fox news.
He was being interviewed on a Latin station about Latin countries, no shit he was asked questions and expected to know. The interviewer was rightly sticking with these questions because, surprise surprise, Latin America is right next to the US and represents a massive voter and demographic base within the US.
This isn't like asking him about Kyrgyzstani trade agreements. This is shit he should know if he agreed to do an interview for Univision. Bernie should have been prepared to answer those questions because of the avenue through which this interview was conducted. It's on him, not the interviewer.
This speaks overwhelmingly to the point that people continue to try and make. That Bernie isn't interested in doing anything but repeating his party line over and over and over again.
And the Ron Paul tactic stops working once people see that there is nothing deeper than that.