Seems very harsh to me. Manufacturer's not honouring warranty's because it has changed ownership doesn't promote green antics in a 'I'm not using this I'll pass it on' kind of way. Also, what with Cotic frames being mail order (mostly) the chances of pople buying worng size frame etc then selling them on will be quite common.
If it was me, I'd hassle Cotic, and maybe settle for a 'deal'. If I didn't get any luck out of them, I'd pop pictures of the frame and crack on a popular mtb forum, saying "look everyone, don't buy one of these, they crack"….. oh hang on…..!