Hmm reading sth like this is a little funny at first but rather disappointing in the end. I am talking about your superiors decisions, of course.
I remember myself reading sth like that 4-5 years ago (how can I convince my boss to use git) and I am going to reproduce a smart answer I read in that thread. No worries just dump them!!! That's it.
I know you probably like them but the meaning of this answer is that since they miss sth obvious like this then they probably miss already many other things too. For sure you don't deserve to struggle that hard to persuade your boss for this. I have some personal experience with some managers who denied the use of some technologies like sass, coffeescript or tools like grunt, gulp, browserify etc because of some stupid reasons and in the end I went away because I want to deal with smart people and not stubborn ones.
Sorry if i have disappointed you, I felt the same back then but now i find this answer quite smart to be honest.
Apart from that you can have a self hosted environment using Gitlab so if you want to push things you have to find a way to implement that kind of solution and present it to them as a working one. Of course as I told you before you are struggling already quite hard.