Any theories?
Probably originated on an Aruba specific forum. People complain about Jews in other places as well, just not (usually) with this term. I did see a couple of people saying "hey, it's not just Aruba, I was in <location> and they were there too!"
FWIW, reading between the lines on one forum, I could see they were struggling between warning travelers of the issue without having a thread for people to curse out Jews. They ended up locking the thread with a stickied warning about Aruba during the 3rd week of January, and then a few warnings about other cities that have disruptive crowds and conventions at different times, again without mentioning ethnicities.