That is not what I said. I said:
if they don't, the female can die
https://en.wikipedia.org/wiki/Ferret_health#Neutering
A female that does not mate can die of aplastic anemia
It has to do with human interference.
Ferrets have survived for a millennia, on several continents, despite human interference.
They were here before us and they will be here after us.
No, it's vermin since if they don't, the female can die.