Another thing by their logic, if the Palestinians really are indigenous (which their not) their "land back" would just mean supporting an independent Palestinian state in the west bank and Gaza strip, just like how land back is here in the United States, and not "From the River to the Sea". Also, where's "From the Pacific to the Atlantic?"
I actually have seen pro-palestinians advocate for the "land back" movement, but that more refers to indigenous sovereignty over historical homeland rather than giving ALL of north America back.