As far I know, its usually the other way around. Slavers actively hunt OSC Linters to...well, surprise! Get their passengers to sell them as slaves. Natually, OSC would be kinda pissed if that stuff happens and maybe even retaliate. But I don't see them actively hunting slavers to free some (poor, unimportant) people, OSC is a commercial venture, and where is the profit in seeking out slavers and freeing people who can't pay you for it?
Only thing I could imagine is that OSC hires some mercs/freelancers to kill slavers in preemtive strikes, and if the freelancer happens to rescue a few slaves...well, great for the public relations department!