They are in a transition phase.
They have rejected the previous regime and want a new one. The current government is now defunct. There is no “law”. In a society that is anarchy and that is really bad to have.
So, the military stepped in as a stop-gap and suspended the constitution. Legally they could not claim a right to run things under that constitution anyway. So, just say it is void till a new one is created. One thing is clear, the people will not abide the current one anyway.
Unfortunately for the Egyptians their revolution has gone like this:
Step 1: Revolution
Step 2: ???
Step 3: Profit!
I have my fingers crossed for the Egyptians but honestly that is about what the protesters had in mind and there is huge opportunity for this to go wrong in any number of ways.
I am not religious by any means but I pray for them (in a generic sorta way).