Horrible idea.
Have you seen what Google has done to YouTube? They push out horrible features without Beta testing it first.
IF, Google acquired Twitter. Twitter would die in about a year because Google would release 0 updates to the site. Just look at Google Plus.
Let’s not forget that anything you type would then be put in Google’s ad system. This would make it where they will target you for that certain object or accessory that you typed in that one tweet.
This is just the start of Google being stupid.