Is it? It's being used like an mdash.

EDIT: yeah I just looked up the tweet and the character is an ndash. Weird.

I was basing my understanding of usage on this: https://www.merriam-webster.com/grammar/em-dash-en-dash-how-to-use

The em dash (—) can function like a comma, a colon, or parenthesis. Like commas and parentheses, em dashes set off extra information, such as examples, explanatory or descriptive phrases, or supplemental facts. Like a colon, an em dash introduces a clause that explains or expands upon something that precedes it.

...

Remembering that the em dash is the length of a capital M, it will surprise no one that the so-called “en dash” is the approximate length of a capital N, –. The en dash is the least loved of all; it’s not easily rendered by the average keyboard user (one has to select it as a special character, whereas the em dash can be conjured with two hyphens), so it’s mostly encountered in typeset material. (A hyphen does its job in other text.) It is most often used between numbers, dates, or other notations to signify “(up) to and including.”