As far as I can tell, Tizen is an excuse for Intel is try to convince Samsung (the largest Android vendor) to produce Atom phones instead of Arm.
Is there anything to indicate there's more to it than this?
The HTML5 aspect reminds me of OS/2's push into Java: "It's ok to safely ignore this platform during your development, it's not like you have to do a _port_ to us or anything, and then when (if) you do get around to testing on us and find out about write-once-debug-everywhere you'll become convinced we're a buggy piece of crap because we're not the reference platform you developed on".
Then there's the "dinosaurs mating" history of all this: Nokia's Maemo merged with Intel's Moblin to form Meego because Maemo and Moblin were both dying. Then that merged with the Limo consortium (these guys: http://www.pcmag.com/article2/0,2817,2258992,00.asp) to form Tizen because Limo was pointless. Saying that the result has significantly fewer users/developers than its components did is NOT a good sign.
Don't get me started on "all the developers of this 'open source' project work at the same company, just like Mozilla under AOL or Open Office under Sun!" Making independent contributors second class citizens doesn't do good things to your code quality...