I'd be more concerned that a staff member wearing makeup and a uniform would pick inappropriate colors or sparkles, such as black or bright purple lipstick, blue or green hair, nails with patterns that glow in the dark, etc. This would require intervention.

However, if OP wants the contract, it could be difficult to fight too much on this issue, especially at contract renewal time. A difficult decision might be necessary. With advance planning, can you assign the good staff agent who doesn't wear makeup to other customers of yours?