I think a Google employee was tasked to remove the search engine choice and hardcode google search into Android.

He didn't want his name to be attached as the person who did this (and we can assume it was some sort of protest to the change) so he committed this as "Anonymous Coward".

Also "Anonymous Coward", as others pointed out, was the way Slashdot referenced guest comments.

> was the way Slashdot referenced guest comments

It still is.

There used to be a search engine switcher view, but google needed to make money.

There used to be a search engine switcher view, but google needed there to be only one correct way of searching the web. so somebody just committed this joke from Slashdot where anons are "anonymous cowards" to remove that previously available option to change engine.

>Why did this commit get accepted in the commit history tree published at android.googlesource.com?

As opposed to what? Do you expect them to maintain an alternate tree without the change that doesn't match published binaries?

Google has an alternate tree. It’s used for prerelease and cancelled hardware, among other things. But probably not for this.

An alternative would have been to bury the change in “misc cleanup” commit. Kudos for at least being honest.