Egotistical males and how they react to my early stage transition femininity

As you might know I work in cosmetics for an amazing company. The only place I am not completely out about my transition is at work so of course I am mostly viewed as a femme male. This brings me to my first personal experience of how some men view what it means to be a women or feminine. 

A man and women walk into my store about my age. Around 28 and I noticed he had a shirt on of a band I love and have loved since I was very young so I commented on how much I loved his shirt and instead of saying thank you and agreeing about how great the band was he instantly responded back with "you don't know anything about metal music" I then proceeded to say is it because I work here and not your normal metal fan. He literally agreed with me that I was "to soft" to like metal music in a true way what ever that is. 

The thing that bothered me the most is my feeling of needing his approval that just because I am an effeminate person that it is possible for me to know as much if not more then he does about the topic we were discussing. 

Honestly speaking this is my first experience being confronted this unmentioned male superiority over me. Mostly I didn't like how I responded, I should have just walked away as opposed to trying to get him to believe I knew what I was talking about. 

And yes all this came from a comment on a band tee.