Well, the Sunni’s actually have no choice. Their former benefactor, the US, has switched sides. They need to ally, quickly, with a superpower. Barring that a regional superpower with nuclear arms will do, even if it’s Israel.
You can throw in what all the other Arabs actually think of the Palestinians and the psychological switch to an alliance of convenience with the Jewish state isn’t all that difficult. The Palestinians have for four generations been an unwelcome irritation for their main hosts, the Jordanians, Egyptians, and Lebanese, and unloved middle management and professionals (doctors and nurses, for example) in all the Arab countries. Easy to replace with South Asian and North African Muslims and totally expendable if or when the time came. They’re lighter skinned, better educated, better off (but not rich), and more clever than the locals, and the objects of envy to the poorer classes. So when a resurgent Shia Persia and their fifth columns present an existential threat turning to the only real super power in the region becomes a no brainer.