How would you get them all from tall trees in rugged terrain t o relocate them? and where would you relocate them to? - if it is another wilderness area they will just die there as well as infect/impact the population i n the new location.
Australian ecosystems may be rugged but they are also fragile - you cant just relocate 16 000 burnt, sick, starving koalas from somewhere else into them.
and how would you feed 16 000 sick and burnt koalas in the wild - they eat a very limited diet and the reason they are starving is the loss of habitat from the fires.
Culling - yes. Isnt this a way of doing that?
I dont think authorities did this because they were gun happy - they did it because there wasn't another way that was feasible.
and for the long run regeneration of the national park, including the koala population, neccesary.