I wouldn't make the assumption that their past is any reliable guide to how they will react to Americans in the future. One can also say that prior to 9/11 terrorists had never attempted to crash hijacked planes into buildings in an American city, yet it would have been wrong to conclude that, therefore, we were in no danger.
I would be more concerned by the fact that the PLO/PA terrorists may regard us as an ally of Israel (which, of course, we are and rightly so). My concern is that they have a ready capacity to commit acts of terrorism against us, regardless of how often or seldom they have exercised that capacity against us in the past.
just like the Mossad could if we forced Israel into an agreement they didnt like. Hell they've fired on our ships and theyve sold our secrets to our enemies.