Seems like a little more 'splaining is necessary!
No, Santis canNOT "hold you" in Mongolia, have no fear. The western embassies have long taken note of Santis' dangerous business practices. Santis cannot and will not be able to hold you or force you to do anything! I mean the US and British embassies. By all means check with them if you wish, they are friendly and both have clean and clear missions - with many a complaint about miserable little Santis' unusual and out of line business practices.
Santis *does ask some of the girls to Friday mixers at the British embassy, true enough. As a teacher I refused because my instinct was not right, uncomfortable. But this does not mean at all that Santis can hold or force people in beautiful Mongolia to do anything out of line!
Mongolia is beautiful, breathtaking! If you are there, enjoy it, get away from Santis and have a great time! 
All I can say it, Santis is already blacklisted, internationally so, and if you go there they will try to mess with you if you are a westerner, especially female. Waste of time and dangerous.