Let me remind you that behing Tizen there is not only Intel but really Samsung. A company obvioulsy interested in the smarthphone and tablet market dominance. Their bussines is hardware, not advertisement , so they are not interested in spreding adware (Android) like Google does. Their dream, like any other company, is to have total control over the software too, so they are backing up software that eventually will fit their needs . So these are not "Tizen-based intel ultrabooks for the community ", there are Samsung ultrabooks with corporate profits in mind. Sadly, there is an obvious conflict of interests with Canonical who is on their way.
At the end, Samsung and Intel can just trash it if their strategies change, just like HP did, jut like Nkia did. Oh! and just like Intel itself did with Tizen ancestors. That's the real world deal.
The whole point of GPL-like licences is not just to "modify the source code for the benefit of anybody else". You are entiled to grab any open source code and modify it for your own personal interests. The license requieres you to publish the source code along with the binaries if you happen to publish your binaries for whatever reason you do it. There is no benefit for the community if there is no individual benefit.
You can fork MIR or Wayland , IF you want for whatever reason you can imagine. There are no arbitrary moral clausules nor obligations in any opensource license.