Killing of innocents deliberately - especially women, children and elderly is terrorism. Regardless of the motivation, this was proven in the life of the prophet and his guidelines for warfare.
Unless those Kibbutz leaders specifically said “kill our women, old men and children” - it was wrong no matter how much suffering their own people caused.
It’s the simple difference of character.
There are arguments on them all being soldiers because they all have to serve - the child has not picked up a rifle yet so they’re out - and if people aren’t picking up weapons yet then they get taken PoWs but not massacred.
Uniformed soldiers - go wild and no international or religious law could say otherwise.