I have no stake in the matter. My supposition that some employees simply stopped working comes from my experience seeing similar things happen at other companies during periods of uncertainty, and from my knowledge that quite a few twitter employees were very uncertain about their future with twitter.
There are people on my team that haven’t committed anything for a couple weeks. I don’t work at Twitter, but wouldn’t be surprised if there were people who basically weren’t working.
I spent the last month prototyping code for a demo that will not be checked in. I have a few small unrelated CLs submitted (minor fixes) but I spent 5 minutes per each, my main work for the month is completely unaccounted for in version control.
For your own sake, you should probably check that demo code in somewhere. Keeping a 'paper' trail of the work you've done is always a good practice to follow.