I doubt his work on the X-Men comic was what got him the job (otherwise why wouldn't Kevin Smith have been on the short list?) and suspect it had more to do with Marvel being able to get Whedon on the cheap compared to more established movie directors.
Nothing Kevin Smith released was as well received as "Astonishing X-Men". It won an Eisner Award which is the comic book equivalent of an Oscar, and is considered the best X-Men story since the 90s.
They've used established movie directors and movie stars for every Marvel film leading up to "The Avengers". So
at them suddenly wanting to get a director "on the cheap" for their biggest movie to date.
So nah. They picked him because he was
that dude in the world of comics at the time. His "geek cred" with stuff like "Buffy", "Angel", "Firefly", etc. obviously didn't hurt either.
Fred.