Then why did Google threaten to banish Acer from the OHA if they dared release even a single device running a fork, partnered with a competing search engine?

Google has made it very clear they are opposed to so-called 'incompatible' forks of Android, and that they consider pretty much anything not running Google's proprietary services to be 'incompatible'.

http://www.theguardian.com/technology/2012/sep/19/android-ch...

> And your app store contains Android apps (including pirated Google apps).

I think THIS was the issue, not the forked Android.

Amazon has a forked Android. Cyanogen has one.

Acer isn't responsible for what Aliyun puts in it's app store, and that's NOT the issue, Google made clear in their response: Google doesn't allow OHA members (companies allowed to ship the Play Store) to sell any devices with forks. Amazon isn't an OHA member. Cyanogen may have something interesting going on, because AFAIK they're compliant with whatever OHA terms they currently have agreed to.

What kind of thinking is that? Google open sourced it because they HAD TO. Linux is GPL so they had no other choice. Whether or not they mind is a different issue.

Indeed, as tingol wrote, parts (as the Linux kernel) had to be open sourced. But also for the large rest I believe open sourcing Android had more advantages than disadvantages for Google - thus it made sense. This does not contradict the fact that Google might not be fond of forks.