That guy is the one who worked with Microsoft to get the bash on Windows thing ready. He has exclusive info and I think his answer to "When?" is pretty straight forward.
I think we have very different ideas of "straight forward". It's not even clear WHAT happens on the 6th. A beta? Hasn't been a beta (or even called a beta) for years. Maybe he means the next Insider Preview? I'd think someone with that kind of access to info would be a little better at communication. I guess when we're trying to decipher cryptic messages, this is what we get.
"Ubuntu on Linux on Windows is in beta form right now". You need to watch the Build2016 live video with the command line team. He is the one with the beard.