But there is also nothing contradictory or wrong with the unit MB.
And I didn't say that. Admittedly, the constraint "If the image size is defined as binary" probably could've been expressed better (I'm not a native speaker). File sizes are usually calculated in binary units (at least by Windows and the Linux distros I know - even though Windows continues to claim those are megabytes and Linux adopted the standardized units) and I'd bet that's the case for file.coffee, too.
Oh, well, I'm pretty sure we're not really disagreeing anyway. So let's conclude with the obligatory relevant xkcd.
Ha, good one! Got me interested, how the standards bodies handle something like that. Found this in the Wikipedia article for byte:
Somewhat disappointing. "There's a conflict but it's fine".