This is like saying:
I am not against taxation. I am against MANDATORY taxation. Do you honestly think that giving people a choice is a bad thing?
No-one wants mandatory military service, but it’s necessary for the sake of society as a whole. Maybe one day it won’t be, but clearly that’s just how things are now.
As for choice, you do have a choice and you know it. Civilian service is a thing here.
Just ask for an extension. Professors have seen this “trick” a thousand times and know exactly what you’re doing. They will respect you more and give you more leeway in the future if you’re straight with them.