We also cannot warranty items that need to be repaired or have defects, this is your risk when purchasing from outside the U.S.
They state it clearly enough, although they could probably add a big, bold, red lettered warning at checkout if you're shipping overseas. In any case, as I see it the questions are (a) is it legal, and (b) is it ethical to require shipping to and from in cases of clear product defects? Regardless of the practicalities of fighting the system or just fixing it yourself, there's still the question of principle.
Of course, one alternative reality would be that Campsaver simply doesn't offer international shipping at all.