I believe FDA has mentioned of some ruling regarding the microbial content of cosmetics (i.e. cosmetics also have microbial specifications).
Having said that, ask yourselves " If we are to allow cosmetics, how can we be sure that its microbial content is within the ACCEPTABLE RANGE? Can you ask your employees who wear makeups to submit as certificate of compliance from their suppliers/brands?" The point is how can we prove that our food handlers are clean if they have on their body something that is considered as "not natural" to their body? (By the way, in food safety, something that is NOT A NATURAL PART of the product's set of ingredients is considered as a CONTAMINANT. With this definition in mind, COSMETICS, then are CONTAMINANTS of the body (being not a natural part of it considerably, right? So the next question, will you allow the contaminant of your body to reach your product? Allowing it will increase the probability of contamination, right?
So, I'll say YES to total ban of cosmetics.
Oh, by the way, before I forgot... allowing "moderate make ups" has big question... How moderate is moderate? How can you distinguish a moderate from a heavy make up? What is your measure? How can you measure? To top it all, it can only trigger an endless debate between the implementors and the subjects. Moreover, it can also be a cause of envy to those not allowed to wear make ups. So you will hear some of your crews... "Why are they allowed to wear make up when our group is prohibited?" Oh, well, another headache.