Sterling, VA, the town next to Herndon, where this took place, is illegal alien central. Several murders there or by its residents have been linked to MS-13 and the 18th Street gang. I won’t be surprised when it turns out that this guy is a Dreamer/gangbanger.
I'm going to guess that MS-13 may have had some concerns about who would have final control of the neighborhood, them or the Muslims, and decided to indicate to the Muslim community that they should move elsewhere.