In the case that a person disliked SWTOR, does it not follow logic that that person would rather play a game they dislike for free than pay to do the same thing?
It makes sense that player populations could drop after the initial free period, the same thing has occurred with other games in the past.
You base all your assumptions off of player population at a certain instant in time, it is not at all representative of player population in the future.
In addition, who knows that "Full" means? It is just an arbitrary meaning that Bioware assigned to a number. It could very well mean 5 people, 50 people, 5000 people...etc.