Depends on your definition of exploit i guess. The game mechanic was put in to boost level 45 players. Some found out that buying a black hole pass would get there level 1 in there and boost it to level 50. The problem actually lies with Bioware allowing level 1 characters to purchase the black hole pass with cartel coins. Hence they cant really punish people as they spent real cash to get there.
But Bioware created the exploit by putting in that legacy / cartel purchase option,