[seabird]

This article also mentions that a large portion of these cases seem to be Muslim. The obvious reasoning behind this is that the Middle East and its large Muslim constituency is one of the US' largest security concerns, and it has been for many years. Things have been happening under the table there since the Iran-Contra affair and probably even before that. I'm willing to wager that the other non-Muslims on this list are from or connected to areas of similar interest (Eastern Europe, South America, North Africa, etc).

The subject of this article may be inadvertently a part of something he has no knowledge of, or may have regular contact with another person of interest who seems otherwise unrelated to his everyday life. There's a lot of possibilities here that don't require the magic power of racism or prejudice to make any sense.