Few people have suffered as much intergenerational trauma as Jewish people. Presumably all their actions in Israel can be explained by this, and we should have a great deal of sympathy for them. Those that survived the holocaust thought they were finally safe, only to be invaded by their neighbours. Those same neighbours have proceeded to attack them non-stop in the intervening years, even overwhelmingly voting in political parties with the sole ambition of murdering them all. This is after centuries of oppression, abuse and genocide wherever they tried to settled, all across the world. And then when they finally thought they might have found peace, when neighbouring countries were accepting them and even the terrorists next door seemed to be working with them, they were attacked, raped and murdered. By the very people to whom they had cautiously started to extend the hand of friendship. Considering all that, they must be a truly remarkable bunch to not be driving cars into crowds, bombing little girls or beheading strangers. Or even burning mosques or massacring Muslims. Though not sure why the palestinians aren't expected to be able to control themselves as well? Do you consider them inferior in some way to Jews?
You also make an extremely good case for why we shouldn't be allowing traumatised refugees into this country. I would absolutely agree that if people suffering trauma, intergenerational or otherwise, are more likely to commit violent crimes, they should be kept well away, and any who have slipped in should probably be removed at the earliest opportunity. Though you say not everyone can be expected to behave in the same way, so are you really claiming it is only Muslims who have this reaction? Are you arguing for only them to be barred?
And as the terrorist in this case was presumably not suffering his own trauma as he was born and raised in Germany long after his parents' country's civil war was over, I'm not sure why he would be compared to a palestinian currently growing up inside a war. You claim you didn't comment only to criticise Israel, so could you please explain exactly what point you were trying to make by connecting the two, and how can intergenerational trauma explain the actions of this particular terrorist. Or are you arguing that any Muslim whose parents might have suffered anything at all traumatic, ever, are a risk? That's an awful lot of people we should be very nervous of then, according to your argument! What do you think we should we do about them...?