@ncoca My two cents is that it was the strangeness of his imprisonment within the Ecuadorian embassy and the ambiguity of what was going to happen to him once arrested. And the fact that is was all playing out in a major western capital. There is also his persona that is ideosyncratic to put it mildly.
I never have seen him as a journalist or a hero (be circumspect of anyone who tells you how brave they are repeatedly) but it was the strangeness of the case that made it stick out.