[Whedon's notoriety] predate[s] "Iron Man" as the catalyst you insist made him get the job.
Did Whedon conceive the franchise mash-up, or was he hired afterwards?
But apparently he told Marvel/Disney/Hollywood he was going to direct "The Avengers" and, being the middle-level player you insist he was, they handed over the keystone of the expensive franchise without hesitation.
Sony spent millions to get the rights to Spider-Man cleared to make the first movie, because they (mistakenly) thought James Cameron was still attached to it. What had Sam Raimi done at that point?