NO, in a catalytic readtion the catalyst remains unchanged. In the catalytic converter of a car the platinum catalyst can be extracted unchanged when the unit is discarded. It is not used up. Super additivity is NOT a catalytic reaction, the Phenidone or Dimezone does get used up. The regeneration of the Phenidone by the ascorbate is not 100% effective.But in the end it has the effect of a catalyst.
When used alone ascorbate ion has a long induction period where no development appears to takr place. This is because it is a negative ion and other negatively charged developer ions behave the same. (An example would be the hydroquinone monosulfonate ion produced by the oxidation of hydroquinone in a sulfite solution.) Given time ascorbate will produce an image. Phenidone and its derivatives have no charge and act more quickly because they are not effected by the charge barrier of the silver halide grains.
I might note that years ago I went around and around with Pat Gainer on this notion and was never able to completely dissabuse him of this idea. I finally gave up.