Of course it's retaliation. Wordpress.org said as much in the announcement - they don't like WP Engine's business model, don't think they contribute enough upstream, etc. And therefore they cut off access to the wordpress.org update servers. Nothing about "practically DDOS" of the server.

Yes, retaliation for using web resources without paying.

> wordpress.org update servers. Nothing about "practically DDOS" of the server

Yes, when you have hundreds of thousands of users this is expensive. What you're describing is expensive.

WPE doesn't maintain these servers, presumably because it's hard and expensive. You can't expect to hit someone's servers with, I'm guessing, hundreds of thousands of requests a day and not pay a dime. If you did that, you would be banned. From just about any free service.

Wordpress.org wrote a whole public post about why they cut off WPE and their reasons are just what I said. I don't understand how you can so confidently assert that the real reason is something different.

It is if they get mad you sent a cease and desist.