The grey area - as per your link - is what is EASA's mandate to legislate over non-EASA registered aircraft just because they reside within the EU?
The first SAFA ramp check August 2016 will be exciting
I'm sorry, but which bit of the following EASA legeslative text
‘Principal place of business’ means the head office or registered office of the organisation within which the principal financial functions and operational control of the activities referred to in this Regulation are exercised.
appears grey to you. That is the definition included and if anyone here doubts that please let me know where in the legislation the phrases "aircraft base" or "where the aircraft resides" is mentioned. Both are absent.
However, I can imagine the overweight, pipe smoking Swiss SAFA inspector (the one with halitosis, and a chip on both shoulders who often polices Samedan) asking for proof of operator's residence. It will be my pleasure to remind him that such a document is not required to be carried on the aircraft, before I ask him to let me on my way!