They are saying it because they hate them.
From Al Monitor/Ammon News:
Former Prime Minister Taher al-Masri wrote in the daily Al Ghad on Dec. 7 that if Israel adopts the law it will “deliver a painful blow to the concept of peace entailed in the 1994 Wadi Araba peace treaty while revealing its true position on a final settlement to the Palestinian problem.” He added that the proposed law is a direct threat to Jordan’s national security.
Masri [="Egyptian" - EoZ], viewed by many as the titular head of Jordanians of Palestinian origin, said that the Nationality Law may cause the transfer of 1.8 million Palestinians to Jordan. He added that Jordan stands to be a casualty of this law...
Adnan Abu Odeh, former chief of the Royal Court, agrees. He told Al-Monitor that passing the law would mean that Israel’s Arab minority, and all other non-Jews, “will be second-class citizens in Israel and will be threatened with transfer.” He added, “Jordan faces two challenges — demographic and geographic.”
“Transferring Israel’s Arabs to the Palestinian territories, as recently suggested by Israeli Foreign Minister Avigdor Liberman, will surely be followed by a mass exodus to Jordan.”
Forget that the idea that Israel will expel its Arab population is ridiculous.Here we have a Palestinian "leader" in Jordan arguing against Jordan allowing those poor, stateless Palestinians to live there!
He really cares about his people, doesn't he?
Of course, major parts of Jordan are actually in "historic Palestine." - if your definition of historic Palestine goes back over a hundred years. For reasons never quite explained, the supposed Palestinians who say they have been there since ancient times never claim eastern Palestine anymore.
If they would, then Jordanians would have reason to be paranoid.