IIRC, everything is gravy because they provided an update for the device (even though it wasn't 6 or 6.1), and they have 6.1 on other phones. Something stupid like that... read the EULA if you want to be sure, I suppose.
*edit*
Meh, totally wrong. They don't sell an upgrade, therefore aren't losing anything. Somebody mentioned the license is for "Windows Mobile", with 6.1 evidently falling under that catagory.
Whatever. If they cared, this site, and xda-devs, would have been gone a long time ago.
Check the thread from XDA:
http://forum.xda-developers.com/showthread.php?t=296359