Send him back to the Phantom Zone. All it would have taken is restructuring the final act so that Zod was in a position--like the rest of the Kryptonian criminals--to be banished.[/QUOTE]
FYI, from the movie it was explained that the only way to open the Zone was for them to turn on the Phantom Drive of the ship they had in hand from the Kent's farm in the proximity of the World builder, which also had a drive. The two fields created the singularity. There was no other Phantom drives left to create the singularity.