Wtf? Even my descriptivist ass is telling whoever came up with that that they're wrong. A burrito is a calzone? An enchilada is sushi? Words mean what you mean when you say them, but they also need to have some structural stability. Out here calling sushi toast. Wtf.
Well of course nigiri sushi isn't a type of sushi.
You think earwigs are an affectation worn by people who are self-conscious about their lack of ear hair? That lightyears are a unit of time? That a urinal cake is a type of lasagna?
When the true Cube Rule believers are rewarded with all manner of toast, sandwiches, tacos, sushi, quiches, calzones, salads, cakes, nachos, and muffins, you'll be sorry you plied your tasteless heresy this day, filthy food miscategorizer! I bet you call hot dogs "sandwiches" like a true troglodite!
A common misconception. You see, nachos are foods composed of a starch within a substrate of non-starch. What you're calling "open faced sandwiches" are a form of "toast" in which non-starch sits atop a layer of starch.