I and possibly many others would have no issue with non-Translink operated buses, such as public or private school buses, wearing the 'Give Way to Bus signs. These signs are used for safety reasons. That is more important, arguing that they should have no signs and putting the lives of children in the bus at risk or accepting that these signs reduce the potential serious injury or death of passengers on buses where the signage is displayed.
Also imagine the alternative scenario that school buses did not have signage and one of these buses was rear ended when trying to re-enter a stream of traffic from a bus stop. There were injuries and/or deaths. I am sure that the parents would be asking many questions of why the school buses didn’t have signage and if it did, would have it prevented the crash. The media and lawyers would also have a field day.
I personally don’t think it is elitist trying to protect the welfare of children.
The signage might also be required by/condition of the school’s insurance company to mitigate risks.