Peace with Egypt has been pretty instrumental to Israel, the basis for peace with all the other Arab states, and that peace has been with Mubarak's government.
In theory, they'd like to support democracy in the middle east (democracies are less likely to go to war with each other)
but when you get right down to it, democracy is government by the people. Egypt's government newspaper has, in this millenium, essentially reprinted the Protocols of the Elders of Zion as fact...
Revolutions are not often conducive to stable governments, and as much as we'd all love for Egypt to become a secular "democracy based on social justice", it could just as easily swing the other way.