If old dough wasn’t used in the formula and if Vit. C were added during one of the later process steps it doesn’t seem it could hurt sponge enzyme activity, though how to dissolve the granules might be an issue unless base formula water was reserved for the purpose.

There’s a good, if at times cryptic, thread at egullet.org about ascorbic acid. That thread mentions some of Calvel’s dough formulas used it. It’s not clear to me whether said formulas are in The Taste of Bread, though that’s my guess. The discussion seems to obliquely reference processes with characteristics similar to Chorleywood without naming them, and hints there may be a longstanding process schism among published experts.

There are also some reasonably specific thoughts on how one might use ascorbic acid over at The Fresh Loaf. The same thread says: “20 ppm (white or cake flour) and 50-60 ppm (whole wheat flour)”, whereas HRUŠKOVÁ1 and NOVOTNÁ2 (pdf study linked in prior comment) appear to have studied 10ppm.

I don’t know anything about the Chorleywood Process except what little I’ve run across online. If I recall correctly, it is a shorter-time dough-process which is manufactured and kneaded using automated factory machines. A search indicates Cauvain and Young wrote a book with the process name in the title that is said to explain the process in some detail, but I’m sorry to report books by those authors are too pricy for me, though it looks like they (same authors have other baking titles) have some fabulous information.

Ascorbic acid is often referred to as a dough conditioner, which as far as I’ve been able to gather allows the simulation of longer-fermented doughs in shorter-fermentation processes with respect to the baked product. I would guess that as an acid, it would also have something of a preserving and/or mold-inhibiting effect, perhaps similar to what I’ve found with vinegar (acetic acid).