GWS approached McCarthy the way our Government treats refugees. It's about instrumentalities. The thinking goes that if we as a country treat refugees badly enough, it might dissuade others from coming.
Similarly, GWS decided to treat McCarthy shabbily by ignoring a potential trade to Freo in order to dissuade other clubs from raiding its AFL-gifted, GWS-developed blue-chip players.
Granted, it's a little callous to compare the persecution of a professional footballer to refugees who, in the majority of cases are fleeing for their lives, but if there was a football equivalent of Nauru, it would probably be South Fremantle.
GWS, like our Government, aren't stupid. They are just incredibly pragmatic and focussed on the long-game, or incredibly mean-spirited, depending on your view.