I think I can shine a little light on this story.
I live and kite in Hua Hin for years and I'm quite familiar with what is going on there in respect of Kiteboarding Asia (KBA) and the other kite shops & schools. First of all, this is not and isolated case. I have personally seen 2 other North kites bought from KBA with cut off serial numbers. KBA is long enough in the business to know exactly what this means: no kite brand will accept any warranty claim without the serial number and an invoice attached to it. So there are absolutely guilty for selling kites without a manufacturers warranty. Period. It does not matter if these kites are seconds or defects or copies or gray imports in that respect. There is no way to find out, but I suspect they are gray imports.
KBA has a long track record in Thailand to offer and sell gear without having a dealership for these brands. To name of few: North, Ozone, F-One, Naish, Slingshot. To my knowledge, the only kite dealerships they have are Cabrinha and Airush. All the foregoing kite brands have other (exclusive) dealers slash distributors in Thailand. So why is this happening? Everybody here knows well, that they continuously try to hurt their competitors in this market with unfair business methods e.g. by offering these brands for 'incredible' prices or publicizing they are the only IKO school and, and...the list is really long. So, some time ago they got caught with gray imports of F-One kites (with serial numbers). A kite brand can trace back with a serial number when/where the kite was manufactured and to whom it was delivered. If a gray import is traced back the company (in another country) it was originally delivered to is immediately in trouble. This is because, like with all other branded products, a distributor who secures rights is also restricted to sell only in the designated territory, normally a country. KBA has obviously sources with dealers in other countries for these brands. These dealers have, if they are not caught, the advantage of meeting their sales targets in a easier way, because they don't have to sell these kites themselves.
To secure a brand like e.g. North in Thailand (BTW the exclusive rights are with North Kiteboarding Club, Hua Hin) requires a substantial investment every year and you need to sell very well to make a living in the kite business. Of course, some (or many?) customers don't care and all what counts is to save somehow 100 bucks, because kite gear is anyway 'way too expensive'. I observed kiters trying out every kiteboard on the rag in legitimate shops, enjoying weeks of free service, counseling, tips, you name it and then walking off to KBA for a little discount. Sounds familiar? If yes, you got what you paid for I guess.
KBA's response is ridiculous. Sure, everybody who exposes these practices is a conman. Give me a break KBA, who are the cons here?? You are rightly reminded of the incredible 'double the warranty' offer publicized on your website: http://www.kiteboardingasia.com/index.php?id=1017
How about it? Probably your customers are just too stupid to understand: 2 times zero is zero! Of course, you sell these brands for incredible prices, but a single warranty claim you have to pay for yourself eats up the tiny margins left over from these sales of gray-imports, isn't it? Here in Hua Hin we are all rolling in the sand laughing!
Well, and then there is this comment in this thread 'there is no such thing as bad publicity'. Well yep, except there is Google. If I am Kiteboarding Asia I would be damn scared that the content this kinda bullshit produces is topping my website sooner or later. But carry on as long as you wish!