You're correct; he leaves out a lot of critical details that, if stated, would paint the Palestinians in a less favorable light. It does not follow that there are not many Palestinian civilians who have been badly mistreated or killed, and that Israel is to significant degree at fault.

But you can't read history impartially without deciding that the Palestinians were initially xenophobic regarding peaceful settlement of Jews (who were buying land) and rejected multiple settlements that while not a great deal for them would have been a lot better than the situation now and arguably a lot more humane than trying to eliminate Israel militarily; and that either we decide in a fit of patronizing colonialism that the Palestinians in Gaza need to be rescued from their nominal leadership, Hamas; or that they do not and thus are willing parties to Hamas' brutality.

One still needn't agree with the ways in which Israel is conducting itself. But, as you have, one ought to doubt that Cory's account is enough to go on on its own.