Almost all nations spy on someone all the time. Sometimes they get caught. Most of the time, except in the case of an actual war, arrangements are made to exchange benefits for the spy's release. It's usually done between the two parties involved. Why is the US carrying Israel's water on this one? If Israel wants its spy released, THEY should make an offer to Egypt.
In three days, Greek coastguard rescues 2,500 migrants (Reuters)
from the article: Report: Egypt may release alleged Israel spy Ilan Grapel