Civil Service Special Leave Entitlement and other issues at an office setting

I am working on one of the support office in a university for less than a year already and the office is managed by an appointed person. There was an upcoming event for the office and I asked for a 3 day leave a two weeks before the event due to some emergencies. I had my outputs ready for checking days before I asked for permission, only then that my boss is busy doing his own business and did not find time to check my work. On the day i asked for permission, he grudgingly told me to file my leave despite of the load of work we have. So i asked him what else I need to do because my outputs were had been ready and waiting for his revisions and approval. He did not answer, all he said was that that time is very crucial for us and there are a lot of things to do like the printing of publicity and tarpaulin which we could not do at the moment because the budget for the activity was not yet approved. I explained to him that I need the leave because of a family emergency but I don't think he listened because he kept on reiterating the load of work but still saying that it is up to me if I still continue my leave. Later that afternoon, he sat on the chair on my colleague's desk and opened the issue of my leave. This time, his voice started to raise and he was saying some not good to hear things on me like I am selfish and does not think of the work to be done and there were students in the area who can hear what he was saying. Then I asked myself why can't he just call me into his office and we can discuss it again privately? Why is there a need to shame someone in public because of that? So my question is that is it possible to deny an employee's request for a leave because of the load of work which in my case I already did my part and it was up to my boss whenever he wants to check on it for approval or revision and that I really need to take my leave because that is a family emergency? and what could the possible legal sanctions on he trying to shame me on public because of the issue of my request? I hope somebody could enlighten me. Thank you.

Based on the org structure of the head and associates, the immediate superior has the discretion to approve/ disapprove leave. This has to be recognized as he has information which you may not be privy to e.g.corporate directions, management instruction etc.

Interpreting your narration, the project is important to him and he may have perceived that you see it as such. I ask you, what is more important, your family or the task and the job? It boils down to communication and relationship. In my opinion, in this situation, it is the associate who adjusts.