So, you’re proposing a non-profit private security firm.
I think your biggest problem, in this day and age of fragmented small interest groups, would be funding. Example:
The KKK has been leaning on local Pakistani people. They contact you for help, and you do. they thank you and give you a donation and angle to have some of their friends do the same. Then the same KKK groups goes after some local Turkish people, and the same thing happens…complete with contributions
Now the fun begins, with a last gasp the local good ol’ boys go after some Jewish people. Being thouroughly versed in their antics, you nip it in the bud really fast. The local Jewish community really gets behind your group and offers various services including backing from their own anti-defamation groups.
Suddenly the Moslem community cools toward you, since you took so long with their problem and acted so fast on the Jewish concerns. Add to that your new ties to the Jewish groups, and they put some distance between themselves and you.
Or, if you turned down the ties to the Jewish groups, the community will then distance itself because they don’t feel comfortable with you now. Either way you loose funding sources.
For even more fun, and draconian measures, substitute racial problems for religious or political ones. Do you think the security NPO would be able to draw support from two, three or four differing groups without loosing one or more of them?
Just something to contemplate at night.