Steven Plaut is clear enough on why Palestinians decided to hang an Italian supporter of Palestinians;
“So just why did the Islamists murder Arrigoni? The answer is simple:
These fanatics believe that everyone who is not a Muslim, and especially not a Muslim of their own particular fundamentalist genre, is an infidel, an enemy, someone deserving death. It does not matter in the least that the infidel in question has come to Gaza to assist the terrorists. In the case of Arrigoni, it did not even matter that he had tattoos on his body endorsing their terrorism. The “bewilderment” being expressed by the ISM and its amen chorus, along with Arrigoni’s Stalinist Italian groupies, is simply further indicative of how little these people know about the Middle East.”
The only people that some Palestinians hate more than Jews is Palestinian supporters who don’t quite fit the picture.