Atheism

No, no, see you're thinking of a group of peace-minded good people following an ancient tradition of love and community... But we're talking about Christians.

They are all about hierarchy and obedience.

Falling out of any norm is an act of disobedience.
You have to be like us to belong to us.
You have to look like us to be like us.
You can't have anything unique to look like us.

Brightly colored hair, tattoos, piercings, non-conformist clothing show that you don't submit an show disobedience.

This is improper.
So you are improper.
Probably dangerous.
Keep away from people like that. You don't wanna be like those.

Is there anything in the Bible about men having short hair?

Considering that we're looking at a Jewish society in Roman times, it's better to look at the Torah. And the answer is...complicated, of course. But the general consensus is that Jewish society felt that long hair was a bad thing for men.

https://torah.org/learning/men-with-long-hair/

However, most Christians cite Paul:

https://biblehub.com/1_corinthians/11-14.htm

Nevermind that Jesus was supposed to predate Paul. The real confusion comes from the Nazarite vows in which men don't cut their hair or bathe for a year before bathing shaving everything off as an act of devotion and renewal. Jesus was allegedly a Nazarene, meaning from the village of Nazareth, and somewhere in all the retellings the two got conflated. So Jesus was frequently depicted with long hair, and only in recent years have new paintings been commissioned showing him with short hair.

Capitalists.