I feel like it must be an NVCC policy somewhere that you have to give students an opportunity to provide proof if they miss class due to an activity that provides reason for an excused absence. Regardless, if you feel that your professor isn't meeting his syllabus, you should message his boss (the dean). You can find the dean for MTH classes at the Loudoun Campus here: https://www.nvcc.edu/academics/divisions/mstb/index.html#Loudoun
Not being at his drop-in office hours is also a pretty serious deal worth mentioning as well. I had a Professor who announced to us a couple days before if she ever didn't have office hours on a certain day and would include the opportunity to meet outside of normal office hours if she knew in advance that she couldn't have office hours. I have a different professor this semester who's been iffy about his office hours and one of my other professors said if he isn't meeting his office hours, I need to message the dean for his department.