Some women are not the LTR types, but enter into those circumstances for some other reason. I suppose a gold-digger would be the most extreme and obvious example of this, although there are many other variations of that. Some women are the LTR types, but will go along with a FWB arrangement reluctantly and temporarily hoping it will turn into something more. Either way, their true intent will be revealed sooner or later.
All I'm really doing is allowing a woman to express what that intent is without apologies. When I tell them "this can be whatever they want it to be", I tend to get more transparency. This benefits me.