It could be argued that such behaviour is inappropriate
The (non-canon) book Vulcan's Forge notes the following Starfleet Regulation:
Regulation 256.15: "Officers shall show professional behavior at all times."
Now, it's important to note that Memory Alpha does clarify that Oo-mox was:
Not strictly sexual
It could be very distracting for a Ferengi and may often be employed by females or males of other species in order to distract a Ferengi during negotiations or to coerce him into an action he would otherwise avoid. (DS9: "Facets")
Whether you consider this course of action to be 'unprofessional', I'll leave it up to you. If you do though, then you could definitely say such action would be 'inappropriate' with regards to Starfleet Regulations!