Of course, by this logic, the crusaders were 100% justified, since they were merely an attempt by Christians to stop the Muslims from ruling over an area -- the holy Land where Jesus lived -- which they saw as theirs.
In fact, by this logic, every agressive war whatever is perfectly justified, since they all start when someone thinks they have a right to something they see as theirs. To give the obvious example, Hitler invaded Poland because he saw the east as Germany's Lebensraum. The Nazis saw it as theirs.
"Yes, but I started the war because I think it's mine" is saying nothing more than "yes, I started the war". In fact it is, at least implicitly, an admission by you that the Arabs did indeed start the war so as to destroy the Jewish state. (Not that there is any need for such admissions -- the Arabs openly and reperatedly said just that at the time, and many still do.)
Why are such weak excuses for genocidal agression considered acceptable when it's the Arabs who are using them against the Jews -- and only in that case?