I took this photo also because of the flag on the jacket of that dude behind the priest of course. He actually was with that priest. I talked to them later at one of the monasteries and they turned out to be Moldovan (but the dude had been living in Italy since he was a kid).
The odds of meeting Moldovans there are actually pretty high because they are one of not that many Europe's Orthodox majority nations and are quite religious too (and it seems to be on the rise there).
Greeks are still the largest group of visitors (Mount Athos is in Greece and it is easier for them to get a permit to visit but they need it too) with the Russians probably being the second largest group (Russia is by far the most populous Orthodox majority country). And then come the Romanians, the Serbians, the Georgians and the rest.
Western Europeans, Americans, Canadians and Australians are not rare too but strangely the percentage of Westerners seems to be higher among the resident monks (quite a lot of them) there than among the visitors.