Because the settlement program did not exist prior to that event.
True only if you continue to frame "settlement" as applying uniquely to Jews/Israelis.
Example:
In 1931 two farmer families purchase land in what will become Area C and each family builds a village. One is Jewish. One is Arab.
In 1948 the Jews are expelled from their village. In 1967 the Arabs are expelled from their village.
Why is it that when the Jews return to their village, they are "settlers" building a "settlement" (with all the negative connotation which has been added to that word over time and has come to specifically mean Jews)?
And yet Arabs are "returning" or "liberating" land which "belongs" to them?
Example:
The JEWISH QUARTER of Jerusalem is considered a "settlement" in "occupied East Jerusalem". The JEWISH QUARTER.
Because it IS in this case - and it isn't how I define - it is how
ISRAEL defines it.
How many Arab settlements have been built since Israel occupied the land? - and yes, at that time occupation was the correct term and the term used by the Israeli's themselves.
Not all or even most of those settlements exist on land previously owned by expelled Jews. You also forget - Palestinians were expelled. Where is their right to create settlements if we are going to be defining it so broadly as to be meaningless? How far back do you go ousting people? If you go back far enough everyone has a right to be there.
Settlements has a meaning and it doesn't have to be Jewish. But it does have to have a real definition, not just a convenient one. It's based on a program - a program with a religiously ordained purpose in this case, but it could be ethnic as well (such as what the Russians did) - of the deliberate settling of people in a region taken in war and under occupation and only that people. It is a program with an intent and typically government support with a motive of securing the territory. Not just people wandering in and moving in during natural migrations. In this case only ONE group gets to create settlements (unless you can give me an actual number of Arab settlements built since the territory was occupied).
It isn't about "right of return" it's about a specific program which has a direct impact on a two state solution. You can keep pretending it doesn't, but it isn't really up to the Jews to claim it doesn't, it's up to the Palestinians to determine whether or not settlements have an effect on the peace process. Just like the Palestinians can't claim "right of return" and Israel having to take in uptillion Palistinians should have no effect on the peace process. It does. From Israel's point of view, it's not up to the Palestinians to say what effects the peace process for the Israeli's.