It is sad and unethical that people are copying your design, but The sad reality is he can't successfully sue them. Having been involved in patents before, his patent most only be provisional(based on the current time frame) at this point.(i'd have to run the patent id with the greek obi to determine) Even if his patent does/is approved by the OBI, it will have no international bearing and would not hold up to court. Greek law is very clear, in pertinent part- Part II General Disposition of Article 5 which lays out many of the requirements to get one's patent approved-
"An invention shall be considered as involving an inventive step if, having regard to the state of the art, it is not obvious to a person skilled in the art"
Unfortunately, his invention is very obvious to anyone skilled in the art. It is nothing that someone skilled in the art wouldn't consider very obvious. Furthermore, A negative ground switch consisting of a spring and brass rod is not patentable, even when combined with an aluminum tube to hold a battery. There are many expired patents covering these type of switches and like
devices. It is also not unique in that it relates to an ecig, as that
device has already been patented.
Even if the Greek obi does approve his patent application it will not hold up under interntional patent law and the patent laws of other countries(in which case, you would have to bring the suit in the country for whom the alleged patent violator resides, which have far more stingent requirements then Greek law)
It is sad downfall to patent law.