These Cotoneasters are well into the Bushland along the Powerline Track. Where do you think they rank on the list of "must get rid ofs"? CNM says they are Noxious or High Risk Weed or Pest but I had an interesting conversation with a ranger about the ecology of little birds using some of the invasive trees/bushes to avoid larger predatory birds. Mind you there are plenty of other bushes in the area where these are. They would be a bugger to pull out - steep slope that is very well vegetated.
Just get rid of any seedlings. Cotoneaster glaucophyllus is a high priority in the List of Naturalised Alien Plants and prohibited (not for sale or propagation) under the Pest Plants regulation. However, mature plants are shelter, habitat and food for native birds and animals, so you need to think of the broader landscape and environment. Sometimes it is better to manage weeds rather than eliminate them.
Photo 2 shows a fairly small plant and plenty of other shrubs nearby. Cut and dab. I am used to seeing cotoneaster 2-3m tall, some of which I leave for later.