Would they not all be better employed pooling their resources and support to put up a mutually agreeable opponent to Blatter to ensure his defeat.
Mind the alternative could be Platini who would possibly be as bad but certainly no better.
I am not sure of how the voting works just a theoretical view of the voting and having numerous candidates. If needed I am sure he would change the rules to ensure he won the vote.
This would appear to be the case and you finish up hypothetically with 5 candidates each getting 15% of the votes and Blatter getting 25% and being reelected by default although 75% voted against him.