I guessed immediately that it was someone from the region...someone who knew exactly what a Sikh's hair means to them...although I would have suspected an Indian national over a Pakistani. The skinheads and other "intolerant" types in the US tend to be damn ignorant and far less likely to know exactly what a Sikh's hair means to them.
This likely isn't racism, many Sikhs and Pakistanis share the same (Punjabi) heritage. I'd say its far more likely that they are the same ethnic group. What this was was an attack on religion.
There really isn't a Western equivalent to this. The closest thing I can think of is perhaps tattooing a Swastika armband on a Jewish person, but the Panj Kakkars (5 gifts) of the Sikh faith are a concept that aren't fully shared by folks of other faith. More often, religion incorporates a change to the body (circumcision) rather than mandating that the body stays untouched.
I think in the West there is a tendency to see religious rituals as that of obligation. You're "forced" to keep your hair long, etc....and its really not.
When it is a part of the faith that you celebrate, having untouched hair is absolutely WONDERFUL.

It something relished and celebrated, and often shared only with one's intimates.

It may sound very strange for someone to read about spiritual value associated with how one's hair, but Amardeep Singh is absolutely correct. Cutting the hair of a Sikh is one of the most devastating things a person can do to an observant Sikh.
He was convicted in 2008 of felony menacing and felony coercion. His sentence was no jail time, 180 days community service, and to tell the judge what he learned about Sikhs.