To claim that Disney was struggling to capture a boy audience is a pretty bold claim.

From the New York Times:

The brooding Marvel characters tend to be more popular with boys — an area where Disney could use help. While the likes of “Hannah Montana” and the blockbuster Princesses merchandising line have solidified Disney’s hold on little girls, franchises for boys have been harder to come by.

Interview with Tom Spurgeon (Comics Journal) in Wall Street Journal:

DJ: What’s Disney’s motivation for acquiring Marvel?
Spurgeon: I think they have a boy need. They seem to do very well with little girls, but not so well with little boys. Especially since they neutered characters like Mickey Mouse and Donald Duck to turn them into corporate icons, more or less they’re safer–they’re not shown with pistols or anything. [Marvel] gives them boy-related content.

Marvel Solves Disney's $50 Billion Boy Problem

How the Walt Disney Company Solved the "Boy Problem"

For a bold claim, it's pretty common.

Which not only defeats his argument...

How does it defeat my argument? You've shown that Disney has made a ton of effort to attract a male demographic. That doesn't mean it worked. All the industry insiders claim Disney had a problem selling merchandise/park tickets/etc. to boys.

You're right that Disney has spent the past 70 years progressively making their traditionally female-focused films more palatable for boys. That doesn't mean that boys responded to those efforts.

Disney has a history of diversifying their material, so why is Maximilian suggesting Disney is being bullied into doing this?

I'm not. I'm only suggesting that Disney is not sexist for using Marvel to solve their boy problem.