Surely the person who 'liberated' the mink is an environmental criminal who has unleashed thousands of predators into an environment that will allow them to cause havoc. It's not the farmer who is showing lack of empathy - it's the nutter releasing mink into the wild.

A lot of the mink will have died once released and those that survive will have gone to find their own territories. They're solitary animals in the wild, so will fight for and defend their territories from others. Again some will die (but that's possible death vs certain death for profit if left in the cages) but the others will be very spread out (they have large territories) so it won't be a case of having a large gang of mink terrorising an area until they've destroyed the eco-system there before moving on.

Non-human animals seem to realise (perhaps not consciously) that if they destroy what they need to survive, they too will die. That's why many animals won't breed if there's not enough food to sustain an increase in numbers and how numbers naturally even themselves out well.

Look at who is really guilty and a criminal here - someone who freed captive, tortured animals, or the person who put them into the cages in the first place and those whose demand for their fur put them there! I used to have mixed feelings on freeing mink too, it's taken me a while to feel this way.