I'm not aware of any difference in legal approach - but I could be wrong. Re your double standards:
In 2015, PA PresidentAbbas amended the law to impose “life imprisonment with forced labor for the duplicitous transfer, leasing or selling of lands to a hostile country or its citizens” while the Palestinians Supreme Fatwa Council declared that selling land to Israelis also violates Islamic law.
If you are not aware then you cannot share that article and see one side of the story only...
For me personally, I understand your point (from a pro-Jewish perspective) regarding reclaiming the land that was taken by Jordan, but in terms of fairness, the same should be applied to the Western part of Jerusalem for the palestinians. In terms of logic, I think it's all bullshit because your claim means the Christian orthodox are also allowed to reclaim Turkey and re-establish the Byzantine empire, the Mongolians should probably also ask to reclaim half of Europe, the native Indians should reclaim the USA etc...
As for Abbas, Abbas is the end-product of Hamas, you cannot expect him to say anything against their doctrine otherwise they remove him. Hamas staying in charge is key to Israel's expansion and taking over Palestinian lands because that is their alibi, and when I say Israel, I mean the government not necessarily the Jewish people (because some of them do oppose this government or the doctrine behind it, they are just too little in numbers/have no effect in altering electoral campaigns), just to avoid the anti-semitic debate all over again.