"On May 7, Israeli forces seized the main border crossing at Rafah, closing a vital route for aid into the besieged enclave."
Understandably, the Egyptian government does not want to coordinate with the Israeli government after seeing how the Israeli-organized aid sites have been going.
That being said Egypt being complicit doesn't make any of this better.
Harboring them was seen by some people as an indirect support to Israeli efforts to push Palestinians out and take over their land.
To this day, any talk about allowing Palestinians to move en masse out of their territory, even as refugees, is at best a very controversial move.
Spitballing here, but it might be continued unease about Arafat. He weaponised the Palestinian population in Lebanon [1] and Jordan [2] in ways that would make it politically untenable for them to accept Palestinian refugees.
[1] https://en.wikipedia.org/wiki/Palestinian_insurgency_in_Sout...
https://www.reuters.com/world/egypt-refuses-coordinate-with-...
https://www.timesofisrael.com/egypt-refusing-to-coordinate-w...
https://www.fdd.org/analysis/2024/05/23/egyptian-blockade-of...