Anyone who knows about the region would see the naivety of suggesting that Egypt/Jordan should take all the ethnically cleansed Palestinians, and Iran has no interest in accepting them. Their involvement is ideological, fighting what they see as the imperialist US and their allies, Palestinians are merely a pawn in their war by proxy. Also they are not Arabs and have a long and well documented history of conflict with them. Especially the more recent Iran/Iraq war where many mercenary fighters serving Saddam were Palestinian, and even now many Palestinian tea shops have a portrait of Saddam, perceived by many as one of the greatest Arab leaders.
So. Is complex.
Egypt is not a rich country unlike some of its neighbours and they already have many refugees. It is not so much about encouraging terrorism is about cost. And ‘yes’ Israel does get the lion’s share of funding over all other countries not just in the ME but worldwide. As for Jordan if they accept more Palestinians, and they already have plenty from decades ago with no right to return, they risk Israel turning its fire power on them in order to defend their borders if there is any unrest, and grabbing land from them.