It is a full-time position, it is not well paid, therefore this staff member has his right to abuse his power and treat people unfairly, is it what you are trying to say?
Following your logic, any educator can consider he/she is unfairly underpaid. A college professor is paid fairly decently, but if you divide the salary with the amount of time he/she has to put into the job, it is much worse that he/she could have acchieved if he/she devoted the energy to earn a professional degree. Does it allow a college professor to start abusing his/her power and unfairly treat his/her students?
This can also apply to other professions. A bank teller is horribly underpaid, do you want to be treatly unfairly next time when you go to the bank?...