Think about what you are saying in relationship to what each step does. The steps are not magic.

The bleach uses it's iron's free electrons (free to the silver, which has a stronger affinity to those electrons than the iron three to iron two step does) to take elemental silver that the developers have acted on and thus remove elemental silver, and return it to it's halogenated state, which the fixer then usually removes.

If you even just partial bleach prior to colour developer, you will be taking part of the image that the colour developer normally would not be acting on (since the first develoiper has already reduced it to elemental silver) and making it a halogen again which would then be fair game for the colour developer to reduce, in adition to the halogens that have been exposed (either optically or chemically) in the reversal step.