The reaction it sounds like says a lot more about the other guy than anything to do with what you are doing. There is a good chance that at some point he might have tried to step out of the status quo and got struck back down so he has learnt a very narrow point of view.
That being said I can understand the desire to hold back from sharing your experiences with others now. But let me tell you one thing, don’t let it hold you back from doing all that you want to whether it is writing on Medium or anything else.