No, I don't buy it either.
Hair is dead, and it made of keratin, not nerve tissue. However, I'll take whatever silly justifications I can when told I "should" cut my hair.
I know I feel better when my hair is long. That's enough for me.
.
Those who want you to doubt that anarchy (self-ownership and individual responsibility) is the best, most moral, and ethical way to live among others are asking you to accept that theft, aggression, superstition, and slavery are better.