I mean, if the workers *are* terrorists then they should be arrested, right? Short of that there are countless ways a non-terrorist can be "linked" with terrorists, and due to the "six degrees of separation" phenomenon it's quite common to have surprising looking connections.
For example Saudi Prince Bandar bin Sultan and I happen to have a common common friend. I met the friend through work and Bandar knew him because his family was a neighbor in Aspen where Bandar has a house. And since Bandar is in the Saudi royal family and Osama bin Laden belonged to a prominent Saudi family, it's almost certain that Bandar knew him from before his Mujahideen days in Afghanistan. So I'm only two two acquaintances removed from Osama bin Laden. That sounds alarming! But in fact I've never *met* Bandar, in fact I've never met any Saudis at all.
I've been racking my brains for people I've met from the actual Middle East, and it turns out that at one point in my career met the Egyptian-American space researcher Farouk el-Baz (who has a TNG shuttlecraft named after him!). El-Baz comes from a connected family; his brother for example was high up in Hosni Mubarak's government, and Farouk himself was at one time a science adviser to Anwar Sadat. It's a fair bet that he knows somebody from Egypt who later went on to be involved with the Muslim Brotherhood -- it wouldn't reflect on him at all. But if that were true I'd be just one acquaintance away from a direct "connection" with the Muslim Brotherhood.
Now it also happens that my wife went to graduate school with someone who was the first woman valedictorian of the US Naval academy. Since I know her directly, I have all kinds of one-degree of separation relationships to people in all kinds of sensitive military and national security positions. I also two different one-degree of separation connections to the Clintons and current Secretary of State John Kerry. If you count my "connections" to my college professors at MIT I'm one-degree of separation away from several Manhattan Project scientists.
If you plotted out my social network to two or three links away it'd look remarkable, in some cases even disturbing. But it's not. "Connection" means almost nothing. There have been cases of people "connected" to terrorists because the frequently called the same number -- a Manhattan pizza restaurant.