That's irrelevant- that's like saying that because the iPad 1 is no longer produced, it therefore rules nothing since it is only sold used and refurbished (like the Touchpad, except that it's new and used).
Used and refurbished are a different market than the new market where this Kindle Fire is coming into. The HP TouchPad is done.
No stock doesn't mean anything- you can pick from thousands on eBay/other resellers who are selling for $300<. It holds a significant place in the tablet market.
No stock = no market share. People don't count used sales for market share analysis. Until a 3rd party OEM licenses webOS, it's not competing with anything.