There will be some more knowledgeable than me who will have a better context, but my limited knowledge of EU regs in a non-aviation context leads me to think that this is a key phrase
If such carriage results in a determination that temporary duty free importation of the aircraft into the EU is not permitted
i.e we aren't normally bothered, but if we think you're taking the p*ss/trying to evade the rules, we reserve the right to clobber you/make life difficult