How could that be a sandwich?! I don't want to cite the dictionary but a sandwich is distinctly a food where fillings are sandwiched by bread. A smørrebrød or tartine can be tasty, but don't claim they're a sammie.
Curious, was the word "sandwich" used in that context before the invention of the sandwich by the Earl of Sandwich?
If not, I don't think you can use a secondary definition of a word as an example for the primary definition when the secondary definition exists solely because of the primary definition.
There was a logical flaw there perhaps, but I stand by my point.
Per a Guardian article linked side-thread, the sandwich was invented by our good Earl for a easily portable and hand-eatable food. One would not call an open-faced nightmare that.
If not, I don't think you can use a secondary definition of a word as an example for the primary definition when the secondary definition exists solely because of the primary definition.