I agree with adding a category back to employment for being employed for sex in some form. If sex is your employment, that should be available to choose, or else you have none to choose.
The fact a relevant option in another trait is available has nothing to do with this trait because you can't pick that trait's option for this trait at all. You still gotta pick something to set preferences, or to express your employment if you want to. Right?
Plus, you can probably have Inexperienced or Virgin characters who're sold into or just starting out in a sex-related trade.
The description of Professional: "A character who is paid professionally to have sex" should be changed into. "A character as experienced as someone who does sex on a professional base" and "Sex" should be added again as option for Employment.
I'm not sure about this because "as experienced as someone who's professional" (at sex) isn't a meaningful comparison. Same thing: you can have inexperienced or, frankly, crap professionals. A lot of the porn stars just know how to fake it for the camera, that's a performance art relevant to the profession, not actual sexual experience (they might still be rubbish in the sack for whoever's boning them on or off set). An Experienced amateur dominatrix could be as skilled as a Professional dominatrix, if not more skilled.
Honestly, thinking about it, Professional makes no sense being stated as a level of sexual experience, because it isn't one. It's a job and should be one. And then you say, after stating you have a job to get paid to have sex (in your Employment trait), how experienced you are at sex.