Not propaganda really, just usual politicians whoring themselves. This looks good on the government to citizens, yay they are saving innocent girls, etc. I suppose one could argue the US can now show it's might as a force for good or whatever based on this, but I'm pretty sure no one is naive enough to buy that these days.
Seems like the better tactic for Boko haram would have been to kill them all, definitely no one would care, no twitter campaign, etc.