I don't see this in any of the formulae. Which one are you referring to?
I understand this compound is used as a UV filter with a cutoff at 398nm. I don't really see how it would be used in a C41 developer.
This is about bleach, not color developer, although it may have something to do with color developer after all.
You may remember the ancient discussions of Microdol vs. Microdol-X, in which the latter one contained some "anti staining compound" to avoid the dichroic fogging problem. Decades of guessing and conjecture ensued, two Kodak patents for such "anti staining compounds" were discovered, one of them Benzophenone, the other one 4-Chloro-Resorcinol. At some point the community settled with "4-Chloro-Resorcinol", and I vaguely remember PE being behind this info.
What I do know is the following: In old times Metol contained a PPD impurity, and PPD without a secondary developer is liable to produce dichroic fog. A decent coupler would quickly scavenge oxidized PPD and thereby avoid the issue. 4-Chloro-Resorcinol is one such coupler, and it yields a well soluble product with oxidized PPD, so this may have well been the reason behind its inclusion in Microdol-X. Note, that this paragraph is my conjecture and not backed up by any credible info.
To come back to the Benzophenone, this was the other compound patented by Kodak to address the dichroic fog problem of Microdol. If it works the same way, then it would scavenge carry over color developer, which would otherwise quickly be oxidized by the ferric PDTA and could potentially stain the film. So this compound could be there for this reason. Again, all amateur level conjecture, no real info from Kodak or real chemists.
I have never seen staining effects with my own ferric PDTA bleach, but compared to what Kodak has seen I have seen pretty much nothing. They surely didn't add this compound just for fun, but the cases where it is really needed may be rare or extreme or both. If you indeed have this kind of staining (some people reported it here when going from C-41 CD directly to Tetenal's BLIX), then a stop and brief wash between CD and bleach is just as effective and likely much cheaper than this Benzophenone compound could ever be.